JP4099218B2 - High corrosion-resistant surface-treated steel sheet and manufacturing method thereof - Google Patents

Description

上記化学構造式中、ｑは０〜５０の整数、好ましくは１〜４０の整数、特に好ましくは２〜２０の整数である。
このようなビスフェノールＡ型エポキシ樹脂は、当業界において広く知られた製造法により得ることができる。
【００４４】
上記エポキシ基含有樹脂（Ｂ）のエポキシ基と反応する活性水素含有化合物としては、下記のものが挙げられる。
・活性水素を有するヒドラジン誘導体
・活性水素を有する第１級または第２級のアミン化合物
・アンモニア、カルボン酸などの有機酸
・塩化水素などのハロゲン化水素類
・アルコール類、チオール類
・活性水素を有しないヒドラジン誘導体または第３級アミンと酸との混合物である４級塩化剤
上記水性エポキシ樹脂分散液を調整する際には、これらの１種または２種以上を使用できるが、優れた耐食性を得るために、活性水素含有化合物の少なくとも一部（好ましくは全部）は、活性水素を有するヒドラジン誘導体であることが必要である。すなわち、これらのうち活性水素を有するヒドラジン誘導体（Ｃ）を必須成分とし、必要に応じてこのヒドラジン誘導体（Ｃ）以外の活性水素含有化合物（Ｄ）を用いる。
【００４５】
上記活性化水素を有するアミン化合物の代表例としては、以下のものを挙げることができる。
(1) ジエチレントリアミン、ヒドロキシエチルアミノエチルアミン、エチルアミノエチルアミン、メチルアミノプロピルアミンなどの１個の２級アミノ基と１個以上の１級アミノ基を含有するアミン化合物の１級アミノ基を、ケトン、アルデヒドまたはカルボン酸と例えば１００〜２３０℃程度の温度で加熱反応させてアルジミン、ケチミン、オキサゾリンまたはイミダゾリンに変性した化合物；
(2) ジエチルアミン、ジエタノールアミン、ジ−ｎ−または−ｉｏｓ−プロパノールアミン、Ｎ−メチルエタノールアミン、Ｎ−エチルエタノールアミンなどの第２級モノアミン；
【００４６】
(3) モノエタノールアミンなどのようなモノアルカノールアミンとジアルキル（メタ）アクリルアミドとをミカエル付加反応により付加させて得られる第２級アミン含有化合物；
(4) モノエタノールアミン、ネオペンタノールアミン、２−アミノプロパノール、３−アミノプロパノール、２−ヒドロキシ−２′（アミノプロポキシ）エチルエーテルなどのアルカノールアミンの１級アミン基をケチミンに変性した化合物；
【００４７】
活性水素含有化合物の一部として使用できる上記４級塩化剤は、活性水素を有しないヒドラジン誘導体または第３級アミンはそれ自体ではエポキシ基と反応性を有しないので、これらをエポキシ基と反応可能とするために酸との混合物としたものである。４級塩化剤は、必要に応じて水の存在下でエポキシ基と反応し、エポキシ基含有樹脂と４級塩を形成する。４級塩化剤を得るために使用される酸は、酢酸、乳酸などの有機酸、塩酸などの無機酸のいずれでもよい。また、４級塩化剤を得るために使用される活性水素を有しないヒドラジン誘導体としては、例えば３，６−ジクロロピリダジンなどを、また、第３級アミンとしては、例えば、ジメチルエタノールアミン、トリエチルアミン、トリメチルアミン、トリイソプロピルアミン、メチルジエタノールアミンなどを挙げることができる。
【００４８】
上記活性水素含有化合物で最も有用で耐食性に優れた性能を発現するのが、活性水素を有するヒドラジン誘導体である。
活性水素を有するヒドラジン誘導体の具体例としては、例えば以下のものを挙げることができる。
▲１▼ カルボヒドラジド、プロピオン酸ヒドラジド、サリチル酸ヒドラジド、アジピン酸ジヒドラジド、セバシン酸ジヒドラジド、ドデカン酸ジヒドラジド、イソフタル酸ジヒドラジド、チオカルボヒドラジド、４，４′−オキシビスベンゼンスルホニルヒドラジド、ベンゾフェノンヒドラゾン、アミノポリアクリルアミドなどのヒドラジド化合物；
▲２▼ ピラゾール、３，５−ジメチルピラゾール、３−メチル−５−ピラゾロン、３−アミノ−５−メチルピラゾールなどのピラゾール化合物；
【００４９】
▲３▼ １，２，４−トリアゾール、３−アミノ−１，２，４−トリアゾール、４−アミノ−１，２，４−トリアゾール、３−メルカプト−１，２，４−トリアゾール、５−アミノ−３−メルカプト−１，２，４−トリアゾール、２，３−ジヒドロ−３−オキソ−１，２，４−トリアゾール、１Ｈ−ベンゾトリアゾール、１−ヒドロキシベンゾトリアゾール（１水和物）、６−メチル−８−ヒドロキシトリアゾロピリダジン、６−フェニル−８−ヒドロキシトリアゾロピリダジン、５−ヒドロキシ−７−メチル−１，３，８−トリアザインドリジンなどのトリアゾール化合物；
【００５０】
▲４▼ ５−フェニル−１，２，３，４−テトラゾール、５−メルカプト−１−フェニル−１，２，３，４−テトラゾールなどのテトラゾール化合物；
▲５▼ ５−アミノ−２−メルカプト−１，３，４−チアジアゾール、２，５−ジメルカプト−１，３，４−チアジアゾールなどのチアジアゾール化合物；
▲６▼ マレイン酸ヒドラジド、６−メチル−３−ピリダゾン、４，５−ジクロロ−３−ピリダゾン、４，５−ジブロモ−３−ピリダゾン、６−メチル−４，５−ジヒドロ−３−ピリダゾンなどのピリダジン化合物；
また、これらのなかでも５員環または６員環の環状構造を有し、環状構造中に窒素原子を有するピラゾール化合物、トリアゾール化合物が特に好適である。
これらのヒドラジン誘導体は１種を単独でまたは２種以上を混合して使用することができる。
【００５１】
以上述べたようなポリアルキレングリコール変性エポキシ樹脂（Ａ）と、このポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）と、さらに必要に応じてこのヒドラジン誘導体（Ｃ）以外の活性水素含有化合物（Ｄ）とを、好ましくは１０〜３００℃、より好ましくは５０〜１５０℃の温度で約１〜８時間反応させ、これにより得られる樹脂を水中に分散させることにより、上述した水性エポキシ樹脂分散液を得ることができる。
【００５２】
上記反応は有機溶剤を加えて行ってもよく、使用する有機溶剤の種類は特に限定されない。例えば、アセトン、メチルエチルケトン、メチルイソブチルケトン、ジブチルケトン、シクロヘキサノンなどのケトン類；エタノール、ブタノール、２−エチルヘキシルアルコール、ベンジルアルコール、エチレングリコール、エチレングリコールモノイソプロピルエーテル、エチレングリコールモノブチルエーテル、エチレングリコールモノヘキシルエーテル、プロピレングリコール、プロピレングリコールモノメチルエーテル、ジエチレングリコール、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノブチルエーテルなどの水酸基を含有するアルコール類やエーテル類；酢酸エチル、酢酸ブチル、エチレングリコールモノブチルエーテルアセテートなどのエステル類；トルエン、キシレンなどの芳香族炭化水素等を例示でき、これらの１種または２種以上を使用することができる。また、これらのなかでエポキシ樹脂との溶解性、皮膜形成性等の面からは、ケトン系またはエーテル系の溶剤が特に好ましい。
【００５３】
ポリアルキレングリコール変性エポキシ樹脂（Ａ）と、ポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）との配合比率は、ポリアルキレングリコール変性エポキシ樹脂（Ａ）およびエポキシ基含有樹脂（Ｂ）中のエポキシ基に対するヒドラジン誘導体（Ｃ）中の活性水素基の当量比が０．０１〜１０、好ましくは０．１〜８、さらに好ましくは０．２〜４となるようにすることが、耐食性や樹脂の水分散性などの観点から適当である。
また、活性水素を有するヒドラジン誘導体（Ｃ）の一部を活性水素含有化合物（Ｄ）に置き換えることもできるが、置き換える量としては９０モル％以下、好ましくは７０モル％以下、より好ましくは１０〜６０モル％の範囲内とすることが防食性、付着性の観点から適当である。
【００５４】
また、緻密なバリア皮膜を形成するために、樹脂組成物中に硬化剤を配合し、皮膜を加熱硬化させることが望ましい。樹脂組成物による皮膜を形成する場合の硬化方法としては、(1)イソシアネートと基体樹脂中の水酸基とのウレタン化反応を利用する硬化方法、(2)メラミン、尿素およびベンゾグアナミンの中から選ばれた１種以上にホルムアルデヒドを反応させてなるメチロール化合物の一部若しくは全部に炭素数１〜５の１価アルコールを反応させてなるアルキルエーテル化アミノ樹脂と基体樹脂中の水酸基との間のエーテル化反応を利用する硬化方法、が適当であるが、このうちイソシアネートと基体樹脂中の水酸基とのウレタン化反応を主反応とすることが特に好適である。
【００５５】
上記(1)の硬化方法で用いることができる硬化剤としてのポリイソシアネート化合物は、１分子中に少なくとも２個のイソシアネート基を有する脂肪族、脂環族（複素環を含む）または芳香族イソシアネート化合物、若しくはそれらの化合物を多価アルコールで部分反応させた化合物である。このようなポリイソシアネート化合物としては、例えば以下のものが例示できる。
【００５６】
▲１▼ ｍ−またはｐ−フェニレンジイソシアネート、２，４−または２，６−トリレンジイソシアネート、ｏ−またはｐ−キシリレンジイソシアネート、ヘキサメチレンジイソシアネート、ダイマー酸ジイソシアネート、イソホロンジイソシアネート
▲２▼ 上記▲１▼の化合物単独またはそれらの混合物と多価アルコール（エチレングリコール、プロピレングリコールなどの２価アルコール類；グリセリン、トリメチロールプロパンなどの３価アルコール；ペンタエリスリトールなどの４価アルコール；ソルビトール、ジペンタエリスリトールなどの６価アルコールなど）との反応生成物であって、１分子中に少なくとも２個のイソシアネートが残存する化合物
これらのポリイソシアネート化合物は、１種を単独でまたは２種以上を混合して使用できる。
【００５７】
また、ポリイソシアネート化合物の保護剤（ブロック剤）としては、例えば、
▲１▼ メタノール、エタノール、プロパノール、ブタノール、オクチルアルコールなどの脂肪族モノアルコール類；
▲２▼ エチレングリコールおよび／またはジエチレングリコールのモノエーテル類、例えば、メチル、エチル、プロピル（ｎ−，ｉｓｏ）、ブチル（ｎ−，ｉｓｏ，ｓｅｃ）などのモノエーテル；
▲３▼ フェノール、クレゾールなどの芳香族アルコール；
▲４▼ アセトオキシム、メチルエチルケトンオキシムなどのオキシム；
などが使用でき、これらの１種または２種以上と前記ポリイソシアネート化合物とを反応させることにより、少なくとも常温下で安定に保護されたポリイソシアネート化合物を得ることができる。
【００５８】
このようなポリイソシアネート化合物（ａ2）は、水性エポキシ樹脂分散液（ａ）（上記成分（ａ））に対して、硬化剤として（ａ）／（ａ2）＝９５／５〜５５／４５（不揮発分の質量比）、好ましくは（ａ）／（ａ2）＝９０／１０〜６５／３５の割合で配合するのが適当である。ポリイソシアネート化合物には吸水性があり、これを（ａ）／（ａ2）＝５５／４５を超えて配合すると表面処理皮膜の密着性を劣化させてしまう。さらに、未反応のポリイソシアネート化合物が上層皮膜中に移動し、上層皮膜の硬化阻害や密着性不良を起こしてしまう。このような観点から、ポリイソシアネート化合物（ａ2）の配合量は（ａ）／（ａ2）＝５５／４５以下とすることが好ましい。
【００５９】
なお、水分散性樹脂は以上のような架橋剤（硬化剤）の添加により十分に架橋するが、さらに低温架橋性を増大させるため、公知の硬化促進触媒を使用することが望ましい。この硬化促進触媒としては、例えば、Ｎ−エチルモルホリン、ジブチル錫ジラウレート、ナフテン酸コバルト、塩化第１スズ、ナフテン酸亜鉛、硝酸ビスマスなどが使用できる。
また、付着性など若干の物性向上を狙いとして、エポキシ基含有樹脂（Ｂ）とともに公知のアクリル、アルキッド、ポリエステル等の樹脂を混合して用いることもできる。
【００６０】
ポリアルキレングリコール変性エポキシ樹脂（Ａ）、エポキシ基含有樹脂（Ｂ）および活性水素を有するヒドラジン誘導体（Ｃ）（さらに必要に応じて活性水素含有化合物（Ｄ））の反応生成物を水分散化するには、例えば以下のような手法を採ることができる。
▲１▼ エポキシ基含有樹脂（すなわち、樹脂（Ａ），（Ｂ））のエポキシ基と活性水素含有化合物である二塩基酸または第２級アミンなどを反応させ、中和剤である３級アミン、酢酸または燐酸などで中和、水分散化させる手法
▲２▼ エポキシ樹脂とポリエチレングリコール、ポリプロピレングリコールなどの末端水酸基含有ポリアルキレンオキサイドをイソシアネートと反応させてなる変性エポキシ樹脂を分散剤に用いて、水分散化させる手法
▲３▼ 上記▲１▼と▲２▼を併用する手法
【００６１】
表面処理組成物には、上述した特定の水分散性樹脂以外に、その他の水分散性樹脂および／または水溶性樹脂として、例えば、アクリル系樹脂、ウレタン系樹脂、ポリエステル系樹脂、エポキシ系樹脂、エチレン系樹脂、アルキッド系樹脂、フェノール樹脂、オレフィン樹脂などの１種または２種以上を、全樹脂固形分中での割合で１５mass％程度を上限として配合してもよい。
【００６２】
次に、上記成分（ｂ）であるシランカップリング剤について説明する。
このシランカップリング剤としては、例えば、ビニルメトキシシラン、ビニルエトキシシラン、ビニルトリクロロシラン、ビニルトリメトキシシラン、ビニルトリエトキシシラン、β−（３，４エポキシシクロヘキシル）エチルトリメトキシシラン、γ−グリシドキシプロピルトリメトキシシラン、γ−グリシドキシプロピルメチルジエトキシシラン、γ−グリシドキシプロピルトリエトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルメチルジメトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルトリメトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルトリメエキシシラン、γ−アミノプロピルトリメトキシシラン、γ−アミノプロピルトリエトキシシラン、γ−メタクリロキシプロピルメチルジメトキシシラン、γ−メタクリロキシプロピルトリメトキシシラン、γ−メタクリロキシプロピルメチルジエトキシシラン、γ−メタクリロキシプロピルトリエトキシシラン、γ−メルカプトプロピルメチルジメトキシシラン、γ−メルカプトプロピルトリメトキシシラン、ｐ−スチリルトリメトキシシラン、γ−アクリロキシプロピルトリメトキシシラン、Ｎ−フェニル−γ−アミノプロピルトリメトキシシラン、γ−ウレイドプロピルトリエトキシシラン、γ−クロロプロピルトリメトキシシラン、ビス（トリエトキシシリルプロピル）テトラスルフィド、γ−イソシアネートプロピルトリエトキシシラン、γ−トリエトキシシリル−Ｎ−（１，３−ジメチル−ブチリデン）プロピルアミン、Ｎ−（ビニルベンジルアミン）−β−アミノエチル−γ−アミノプロピルトリメトキシシランなどを挙げることができ、これらの１種を単独でまたは２種以上を混合して使用することができる。
【００６３】
本発明において、表面処理組成物が特定の酸成分とともにシランカップリング剤を含むことにより耐白錆性が向上するには、先に述べたような理由が考えられる。
また、上記シランカップリング剤のなかでも、上記成分（ａ）の水分散性樹脂と反応性が高い官能基を有するという観点から、特に反応性官能基としてアミノ基を有すシランカップリング剤が好ましい。このようなシランカップリング剤としては、例えば、Ｎ−β（アミノエチル）γ−アミノプロピルメチルジメトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルトリメトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルトリメエキシシラン、γ−アミノプロピルトリメトキシシラン、γ−アミノプロピルトリエトキシシランなどが挙げられ、具体的には、信越化学（株）製の「ＫＢＭ−９０３」、「ＫＢＥ−９０３」、「ＫＢＭ−６０３」、「ＫＢＥ−６０２」、「ＫＢＥ−６０３」（いずれも商品名）などを用いることができる。
【００６４】
シランカップリング剤の配合量は、上記成分（ａ）である水性エポキシ樹脂分散液の固形分１００質量部に対して１〜３００質量部、好ましくは５〜１００質量部、さらに好ましくは１５〜５０質量部とするのが適当である。シランカップリング剤の配合量が１質量部未満では耐食性が劣り、一方、３００質量部を超えると十分な皮膜が形成できないため、水分散性樹脂との密着性とバリア性を高める効果が発揮できず、耐食性が低下する。
【００６５】
次に、上記成分（ｃ）であるリン酸および／またはヘキサフルオロ金属酸は、不活性なめっき金属表面に作用してめっき金属表面を活性化させる作用を有する。このリン酸とヘキサフルオロ金属酸はそれぞれ単独で用いてもよいし、併用してもよい。
ヘキサフルオロ金属酸の種類は特に限定されないが、特にフッ化チタン酸、フッ化ジルコン酸、けいフッ酸などのようなＴｉ、Ｓｉ、Ｚｒの中から選ばれる１種以上の元素を含むヘキサフルオロ金属酸が好ましく、これらの１種または２種以上を用いることができる。
【００６６】
リン酸および／またはヘキサフルオロ金属酸の配合量は、上記成分（ａ）である水性エポキシ樹脂分散液の固形分１００質量部に対して、合計で０．1〜８０質量部、好ましくは１〜６０質量部、さらに好ましくは５〜５０質量部とするのが適当である。リン酸および／またはヘキサフルオロ金属酸の配合量が０．１質量部未満では耐食性が劣り、一方、８０質量部を超えると皮膜の可溶成分が増えることから、耐食性が低下するため好ましくない。
【００６７】
表面処理組成物には、耐食性向上を目的として、必要に応じて水溶性リン酸塩を配合することができる。この水溶性リン酸塩としては、例えば、オルトリン酸、ピロリン酸、ポリリン酸、メタリン酸などの金属塩の１種又は２種以上を用いることができる。また、有機リン酸の塩（例えば、フィチン酸、フィチン酸塩、ホスホン酸、ホスホン酸塩およびこれらの金属塩）の１種以上を添加してもよい。また、それらのなかでも第一リン酸塩が表面処理組成物の安定性などの面から好適である。
皮膜中でのリン酸塩の存在形態も特別な限定はなく、また、結晶若しくは非結晶であるか否かも問わない。また、皮膜中でのリン酸塩のイオン性、溶解度についても特別な制約はない。水溶性リン酸塩を配合することにより耐食性が向上する理由は、水溶性リン酸塩が皮膜形成時に緻密な難溶性化合物を形成するためであると考えられる。
【００６８】
先に述べたようにシランカップリング剤は活性化されためっき金属と皮膜形成樹脂の両方と化学結合することで、めっき金属と皮膜形成樹脂との優れた密着性と耐食性が得られるが、めっき金属表面には不可避的に不活性な部分が存在し、このような不活性なサイトでは上記化学結合が生じにくく防錆効果を十分発揮できない。水溶性リン酸塩はこのようなめっき皮膜の部分に対して、皮膜形成時に緻密な難溶性化合物を形成する。すなわち、水溶性リン酸塩のリン酸イオンによるめっき皮膜の溶解に伴いめっき皮膜／表面処理組成物界面でｐＨが上昇し、その結果、水溶性リン酸塩の沈殿物皮膜が形成され、これが耐食性の向上に寄与する。
【００６９】
また、特に優れた耐食性を得るというの観点からは、水溶性リン酸塩のカチオン種としてはＡｌ、Ｍｎ、Ｎｉ、Ｍｇが特に望ましく、これらの中から選ばれる１種以上の元素を含む水溶性リン酸塩を用いることが好ましい。このような水溶性リン酸塩としては、例えば、第一リン酸アルミニウム、第一リン酸マンガン、第一リン酸ニッケル、第一リン酸マグネシウムが挙げられ、これらのうちでも特に第一リン酸アルミニウムが最も好ましい。また、そのカチオン成分とＰ_２Ｏ_５成分のモル比［カチオン］／［Ｐ_２Ｏ_５］は０．４〜１．０であることが好ましい。モル比［カチオン］／［Ｐ_２Ｏ_５］が０．４未満では可溶性のリン酸によって皮膜の難溶性が損なわれ、耐食性が低下するので好ましくない。一方、１．０を超えると処理液安定性が著しく失われるので好ましくない。
【００７０】
この水溶性リン酸塩の配合量は、上記成分（ａ）である水性エポキシ樹脂分散液の固形分１００質量部に対して、固形分の割合で０．１〜６０質量部、好ましくは０．５〜４０質量部、さらに好ましくは１〜３０質量部とするのが適当である。水溶性リン酸塩の配合量が０．１質量部未満では耐食性の向上効果が十分でなく、一方、６０質量部を超えると皮膜の可溶成分が増えることから、耐食性が低下するため好ましくない。
【００７１】
表面処理組成物には、耐食性向上を目的として、必要に応じて非クロム系防錆添加剤を配合することができる。表面処理組成物中にこのような非クロム系防錆添加剤を配合することにより、特に優れた防食性能（自己補修性）を得ることができる。
この非クロム系防錆添加剤は、特に下記（ｅ1）〜（ｅ5）の中から選ばれる１つ以上を用いることが好ましい。
（ｅ1）酸化ケイ素
（ｅ2）カルシウム又はカルシウム化合物
（ｅ3）難溶性リン酸化合物
（ｅ4）モリブデン酸化合物
（ｅ5）トリアゾール類、チオール類、チアジアゾール類、チアゾール類、チウラム類の中から選ばれる１種以上の、Ｓ原子を含有する有機化合物
これら（ｅ1）〜（ｅ5）の非クロム系防錆添加剤の詳細及び防食機構は以下の通りである。
【００７２】
まず、上記（ｅ1）の成分としては微粒子シリカであるコロイダルシリカや乾式シリカを使用することができるが、耐食性の観点からは特に、カルシウムをその表面に結合させたカルシウムイオン交換シリカを使用するのが望ましい。
コロイダルシリカとしては、例えば、日産化学（株）製のスノーテックスＯ、２０、３０、４０、Ｃ、Ｓ（いずれも商品名）を用いることができ、また、ヒュームドシリカとしては、日本アエロジル（株）製のＡＥＲＯＳＩＬ Ｒ９７１、Ｒ８１２、Ｒ８１１、Ｒ９７４、Ｒ２０２、Ｒ８０５、１３０、２００、３００、３００ＣＦ（いずれも商品名）を用いることができる。また、カルシウムイオン交換シリカとしては、W.R.Grace＆Co．製のＳＨＩＥＬＤＥＸ Ｃ３０３、ＳＨＩＥＬＤＥＸ ＡＣ３、ＳＨＩＥＬＤＥＸ ＡＣ５（いずれも商品名）、富士シリシア化学（株）製のＳＨＩＥＬＤＥＸ、ＳＨＩＥＬＤＥＸ ＳＹ７１０（いずれも商品名）などを用いることができる。これらシリカは、腐食環境下において緻密で安定な亜鉛の腐食生成物の生成に寄与し、この腐食生成物がめっき表面に緻密に形成されることによって、腐食の促進を抑制する。
【００７３】
また、上記（ｅ2）、（ｅ3）の成分は沈殿作用によって特に優れた防食性能（自己補修性）を発現する。
上記（ｅ2）の成分であるカルシウム化合物は、カルシウム酸化物、カルシウム水酸化物、カルシウム塩のいずれでもよく、これらの１種または２種以上を使用できる。また、カルシウム塩の種類にも特に制限はなく、ケイ酸カルシウム、炭酸カルシウム、リン酸カルシウムなどのようなカチオンとしてカルシウムのみを含む単塩のほか、リン酸カルシウム・亜鉛、リン酸カルシウム・マグネシウムなどのようなカルシウムとカルシウム以外のカチオンを含む複塩を使用してももよい。この（ｅ2）の成分は、腐食環境下においてめっき金属である亜鉛やアルミニウムよりも卑なカルシウムが優先溶解し、これがカソード反応により生成したＯＨ⁻と緻密で難溶性の生成物として欠陥部を封鎖し、腐食反応を抑制する。また、上記のようなシリカとともに配合された場合には、表面にカルシウムイオンが吸着し、表面電荷を電気的に中和して凝集する。その結果、緻密で且つ難溶性の保護皮膜が生成して腐食が封鎖し、腐食反応を抑制する。
【００７４】
また、上記（ｅ3）である難溶性リン酸化合物としては、難溶性リン酸塩を用いることができる。この難溶性リン酸塩は単塩、複塩などの全ての種類の塩を含む。また、それを構成する金属カチオンに限定はなく、難溶性のリン酸亜鉛、リン酸マグネシウム、リン酸カルシウム、リン酸アルミニウムなどのいずれの金属カチオンでもよい。また、リン酸イオンの骨格や縮合度などにも限定はなく、正塩、二水素塩、一水素塩または亜リン酸塩のいずれでもよく、さらに、正塩はオルトリン酸塩の他、ポリリン酸塩などの全ての縮合リン酸塩を含む。この難溶性リン化合物は、腐食によって溶出しためっき金属の亜鉛やアルミニウムが、加水分解により解離したリン酸イオンと錯形成反応により緻密で且つ難溶性の保護皮膜を生成して腐食起点を封鎖し、腐食反応を抑制する。
【００７５】
また、上記（ｅ4）のモリブデン酸化合物としては、例えば、モリブデン酸塩を用いることができる。このモリブデン酸塩は、その骨格、縮合度に限定はなく、例えばオルトモリブデン酸塩、パラモリブデン酸塩、メタモリブデン酸塩などが挙げられる。また、単塩、複塩などの全ての塩を含み、複塩としてはリン酸モリブデン酸塩などが挙げられる。モリブデン酸化合物は不動態化効果によって自己補修性を発現する。すなわち、腐食環境下で溶存酸素と共にめっき皮膜表面に緻密な酸化物を形成することで腐食起点を封鎖し、腐食反応を抑制する。
【００７６】
また、上記（ｅ5）の有機化合物としては、例えば、以下のようなものを挙げることができる。すなわち、トリアゾール類としては、１，２，４−トリアゾール、３−アミノ−１，２，４−トリアゾール、３−メルカプト−１，２，４−トリアゾール、５−アミノ−３−メルカプト−１，２，４−トリアゾール、１Ｈ−ベンゾトリアゾールなどが、またチオール類としては、１，３，５−トリアジン−２，４，６−トリチオール、２−メルカプトベンツイミダゾールなどが、またチアジアゾール類としては、５−アミノ−２−メルカプト−１，３，４−チアジアゾール、２，５−ジメルカプト−１，３，４−チアジアゾールなどが、またチアゾール類としては、２−Ｎ，Ｎ−ジエチルチオベンゾチアゾール、２−メルカプトベンゾチアゾール類などが、またチウラム類としては、テトラエチルチウラムジスルフィドなどが、それぞれ挙げられる。これらの有機化合物は吸着効果によって自己補修性を発現する。すなわち、腐食によって溶出した亜鉛やアルミニウムがこれらの有機化合物が有する硫黄を含む極性基に吸着して不活性皮膜を形成することで腐食起点を封鎖し、腐食反応を抑制する。
【００７７】
非クロム系防錆添加剤の配合量は、上記成分（ａ）である水性エポキシ樹脂分散液の固形分１００質量部に対して、固形分の割合で０．1〜５０質量部、好ましくは０．５〜３０質量部とするのが適当である。この非クロム系防錆添加剤の配合量が０．１質量部未満では、耐アルカリ脱脂後の耐食性向上効果が十分に得られず、一方、５０質量部を超えると塗装性及び加工性が低下するだけでなく、耐食性も低下するので好ましくない。
なお、上記（ｅ1）〜（ｅ5）の防錆添加剤を２種以上複合添加してもよく、この場合にはそれぞれ固有の防食作用が複合化されるため、より高度の耐食性が得られる。特に、上記（ｅ1）の成分としてカルシウムイオン交換シリカを用い、且つこれに（ｅ3）、（ｅ4）、（ｅ5）の成分の１種以上、特に好ましくは（ｅ3）〜（ｅ5）の成分の全部を複合添加した場合に特に優れた耐食性が得られる。
【００７８】
また、表面処理皮膜（および表面処理組成物）中には、腐食抑制剤として、他の酸化物微粒子（例えば、酸化アルミニウム、酸化ジルコニウム、酸化チタン、酸化セリウム、酸化アンチモンなど）、リンモリブデン酸塩（例えば、リンモリブデン酸アルミニウムなど）、有機インヒビター（例えば、ヒドラジンおよびその誘導体、チオール化合物、チオカルバミン酸塩など）などの１種または２種以上を添加できる。
【００７９】
さらに必要に応じて、表面処理皮膜（および表面処理組成物）中には添加剤として、有機着色顔料（例えば、縮合多環系有機顔料、フタロシアニン系有機顔料など）、着色染料（例えば、水溶性アゾ系金属染料など）、無機顔料（例えば、酸化チタンなど）、導電性顔料（例えば、亜鉛、アルミニウム、ニッケルなどの金属粉末、リン化鉄、アンチモンドープ型酸化錫など）、カップリング剤（例えば、チタンカップリング剤など）、メラミン・シアヌル酸付加物などの１種または２種以上を添加することができる。
以上のような成分を含む表面処理組成物により形成される表面処理皮膜は、乾燥膜厚が０．０１〜１．０μｍ、好ましくは０．１〜０．８μｍとする。乾燥膜厚が０．０１μｍ未満では耐食性が不十分であり、一方、１．０μｍを超えると導電性や加工性が低下する。
【００８０】
次に、以上述べた表面処理皮膜の具体的な皮膜構造について説明する。
本発明において亜鉛系めっき鋼板またはアルミニウム系めっき鋼板の表面に形成される表面処理皮膜の皮膜構造は、Ｐ、Ｚｎまたは／およびＡｌ、およびＯを含有する非晶質化合物層と、その上層のヒドラジン誘導体で変性した特定のエポキシ基含有樹脂、すなわち、数平均分子量４００〜２００００のポリアルキレングリコール、ビスフェノール型エポキシ樹脂、活性水素含有化合物およびポリイソシアネート化合物を反応させて得られたポリアルキレングリコール変性エポキシ樹脂（Ａ）と、このポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）と、さらに必要に応じてこのヒドラジン誘導体（Ｃ）以外の活性水素含有化合物（Ｄ）とを反応させて得られた水分散性樹脂をマトリックスとする有機樹脂マトリックス層とからなるもので、好ましくは皮膜（非晶質化合物層または／および有機樹脂マトリックス層）中に、Ｐ、Ｚｎまたは／およびＡｌ、およびＯを含む析出化合物、さらに好ましくはＰ、Ｚｎまたは／およびＡｌ、ＳｉおよびＯを含む析出化合物を含有したものである。この表面処理皮膜はクロムを全く含まない。
【００８１】
亜鉛系めっき鋼板などの下地めっき鋼板に、クロムフリー皮膜によって優れた耐食性（耐白錆性）を付与するためは、先に述べたように、
▲１▼ 有機樹脂によって腐食因子の拡散障壁となる高度なバリア層を形成し、カソード反応を抑制する。
▲２▼ 表面処理組成物とめっき皮膜表層との反応によってめっき皮膜表層に緻密な不活性層（反応層）を形成し、この不活性層によるめっき皮膜表面の不活性化作用によってアノード反応を抑制する。
ことが効果的であり、さらに好ましくは、
▲３▼ 上記不活性層の欠損部分（若しくは破損部分）と反応してこれを修復し、その部分から溶出しようとする亜鉛イオンなどの金属イオンを捕捉・難溶化する自己補修物質を有する（すなわち、自己補修性を有する）。
ことが効果的である。
【００８２】
本発明の表面処理鋼板が有する上記表面処理皮膜によれば、上層側の有機樹脂マトリックス層によって高度のバリア性（上記▲１▼の作用）が付与されるとともに、下層側の非晶質化合物層によってめっき皮膜表層の不活性化作用（上記▲２▼の作用）が付与され、さらに、好ましくは皮膜中に含有する析出化合物により自己補修性（上記▲３▼の作用）が付与され、これらの複合的な作用により表面処理鋼板に高度な耐食性が付与されることになる。
上記非晶質化合物層は、表面処理組成物とめっき皮膜表層とが反応することにより生成した非晶質化合物の濃化層ないし皮膜であり、めっき皮膜成分であるＺｎ，Ａｌに由来するＺｎまたは／およびＡｌを含む化合物からなるものである。めっき鋼板が亜鉛系めっき鋼板である場合、上記非晶質化合物の組成上の特徴は、ＺｎとＰを等モル含むこと、より具体的には、ＺｎとＰのモル比［Ｚｎ］／［Ｐ］が０．９〜１．４である点にある。この化合物は第二リン酸塩系の化合物（例えば、ＺｎＨＰＯ_４・２Ｈ_２Ｏ）であると推定される。
【００８３】
このような非晶質化合物層が形成されることにより優れた耐白錆性が得られるのは、すでに述べたように、この非晶質化合物層がめっき層表層を不活性化することにより、腐食因子が上層側のバリア層(有機樹脂マトリックス層)を突き抜けてめっき皮膜の表面に至っても、白錆の発生に関わるアノード反応が抑制されるためであると考えられる。
この非晶質化合物層の層厚は、耐食性の点から１０ｎｍ以上であることが好ましい。
非晶質化合物層を積極的に形成させるためには、表面処理組成物を塗布した後の加熱処理を誘導加熱方式（誘導加熱炉）で行うことが好ましい。これは、誘導加熱方式による加熱では、鋼板側から加熱されるためめっき皮膜と表面処理組成物との反応が促進され、非晶質化合物層の生成に有利な条件となるからである。
【００８４】
表面処理皮膜は、通常、表面処理組成物に含まれるシランカップリング剤に由来するシラン化合物を含有している。なお、このシラン化合物は、シランカップリング剤としての組成で含有されている場合も含む。
また、表面処理皮膜により高度な耐白錆性を付与するためには、表面処理皮膜が特定の析出化合物を含有することが好ましい。この析出化合物は、Ｐ、Ｚｎまたは／およびＡｌ、及びＯを含む非晶質の析出化合物であり、さらにこの析出化合物がＳｉを含むことにより、耐白錆性の向上効果がより高められる。この析出化合物中に含まれるＺｎ，Ａｌはめっき皮膜成分であるＺｎ，Ａｌに由来するものであり、また、Ｓｉは表面処理組成物に含まれるシランカップリング剤に由来するものである。
【００８５】
上記析出化合物は、めっき皮膜から溶解しためっき金属と表面処理組成物中の主として酸成分との反応生成物（化合物）であると考えられ、表面処理組成物中に適量の酸成分（リン酸など）を含ませることにより皮膜中に生成（析出）させることができる。また、上記析出物のうち、Ｓｉを含有する析出化合物は、表面処理組成物中のシランカップリング剤成分が化合物中に取り込まれたものであり、このような析出化合物も表面処理組成物中のシランカップリング剤の添加量を適正化（添加量を比較的多目にする）することにより皮膜中に生成（析出）させることができる。
【００８６】
表面処理皮膜中に上記析出化合物が含有されることにより耐白錆性が向上する理由は必ずしも明らかではないが、析出化合物から溶出したリン酸イオンなどの酸成分が、腐食過程でめっき皮膜から溶出した亜鉛イオンなどの金属イオンと結合して不溶性化合物が生成され、安定な沈殿保護皮膜を形成して腐食を抑制する（自己補修性を発揮する）ためであると推定される。
また、析出化合物にＳｉが含まれることによって、より優れた耐白錆性が得られる理由も必ずしも明らかではないが、Ｓｉの含有によって腐食環境下での析出化合物の溶解性が高まること、析出化合物中のＳｉが非晶質化合物層に取り込まれることにより、腐食過程でめっき皮膜から溶出する亜鉛イオンなどの金属イオンとの反応生成物がより安定になること、などの要因が考えられる。
めっき鋼板が亜鉛系めっき鋼板である場合、通常、表面処理皮膜が含有する析出化合物はＺｎとＰを等モル含むものである。より具体的には、ＺｎとＰのモル比［Ｚｎ］／［Ｐ］が０．９〜１．４であり、この化合物は第二リン酸塩系の化合物（例えば、ＺｎＨＰＯ_４・２Ｈ_２Ｏ）であると推定される。
【００８７】
一方、表面処理皮膜中にＺｎとＰのモル比[Ｚｎ]／［Ｐ］が１．０未満である析出化合物を析出させた場合には、ＺｎとＰを等モル含む析出化合物を析出させた場合に較べて耐白錆性がより向上する。このモル比［Ｚｎ］／［Ｐ］が１．０未満の析出化合物は、水に可溶な第一リン酸塩（例えば、Ｚｎ（Ｈ_２ＰＯ_４）_２・Ｈ_２Ｏ）主体の化合物であると推定される。このような化合物を析出させることによって特に優れた耐白錆性が得られる理由は必ずしも明らかではないが、この析出化合物が、非晶質化合物層の欠損部分から溶出しようとする亜鉛イオンなどの金属イオンと反応して、難溶性の第二リン酸塩（例えば、第二リン酸亜鉛）を形成することで、自己補修物質としての高度の機能を果たすためであると推定される。
【００８８】
以上述べた表面処理皮膜の膜厚は、先に述べたように、０．０１〜２．０μｍ、好ましくは０．１〜１．５μｍである。また、表面処理皮膜中には、先に述べたように非クロム系防錆添加剤、固形潤滑剤などを含有させることができる。
また、表面処理皮膜を形成するための表面処理組成物は、上述したような化合物層（非晶質化合物層）や析出化合物を生成させるため水溶媒系のものである必要があり、したがって、有機樹脂としては水分散性樹脂が用いられる。
【００８９】
次に、上述した表面処理皮膜の皮膜組成の測定方法の詳細について説明する。現在広く用いられている透過電子顕微鏡、エネルギー分散型Ｘ線分析装置により求めた皮膜断面の局所的な組成の定量値は、断面試料の作成方法、データの測定条件、データ処理法、定量補正計算法などによって変わってしまうのが実態である。これは、▲１▼透過電子顕微鏡で観察可能な未知試料に適した元素分析用標準試料を逐次準備することが実質的に不可能であるため、標準試料を用いない理論計算に基づく定量計算を採用せざるを得ず、そのための計算モデルが多様である、▲２▼Ｎａ以下の軽元素に対するＮａ以上の重元素の相対濃度の定量計算方法が世界的にも確立されていない、などの理由によるものである。こうした状況に加えて、断面試料の形状や断面試料の支持台などに起因する、測定対象部分以外からの特性Ｘ線の取り扱い方も定量結果を大きく左右する。
【００９０】
そこで、本発明では、上記皮膜組成の測定に以下のような方法を用いた。まず、透過電子顕微鏡用の断面試料の作成には、日立製作所社製の収束イオンビーム加工装置（Focused Ion Beam: ＦＩＢ）ＦＢ２０００Ａに付設したマイクロサンプリング機構を用いた。なお、ＦＩＢ加工に先立って、断面試料を作成する表面処理鋼板の試料片の表面には、イオンビーム照射によるダメージからこれを保護するため、Ｃの保護膜を２００ｎｍ前後フラッシュ蒸着し、その上にさらにＡｕの保護膜を約１００ｎｍスパッタコーティングした。ＦＩＢ加工装置に導入した供試材の断面試料切り出し部分の表面には、ＦＩＢ加工装置の化学気相蒸着（ＣＶＤ）機構を用いてさらにＣ保護膜を５００ｎｍ前後被覆した上で、断面試料の切り出し加工を行った。マイクロサンプリング機構を用いて取り出した断面試料は、Ｍｏ製の半月板状特殊メッシュの直線部分にＣＶＤ機構を利用して固定した上で、透過電子顕微鏡観察に適する膜厚まで仕上げた。
このようにして作成した断面試料の組成分析には、電界放出型電子銃を搭載したPhilips社製の透過電子顕微鏡ＣＭ２０ＦＥＧと、これに付設したSuper-ＵＴＷ型検出器を備えたEDAX社製のエネルギー分散型Ｘ線分析装置Phoenixを用いた。なお、顕微鏡像観察ならびに元素分析時の加速電圧はいずれも２００ｋＶとした。
【００９１】
非晶質化合物層および析出化合物の組成は、これらの位置から収集したスペクトルデータからバックグラウンド除去・ピーク分離・定量補正計算を行って求めた。その際、バックグラウンド処理を自動で行うと軽元素域での正味の強度（ネット強度）が適切に計算されない場合があるため、ピークが出現しないエネルギー位置をマニュアルで指定し、これを結ぶマニュアルバックグラウンド方式で処理（除去）した。ピーク分離では、断面試料の支持台として使用するＭｏメッシュやＡｕの保護層に起因するＭｏとＡｕ、ＦＩＢ加工に起因するＧａなどの特性Ｘ線も考慮した。定量計算はいずれも化成処理皮膜に含まれる各元素のＫ系列の特性Ｘ線を用いて行った。なお、補正計算は薄膜近似で行い、補正因子（いわゆるＫ_ＡＢ因子）にはZaluzecのモデルを使用した。
表面処理皮膜の非晶質化合物層および析出化合物のＺｎとＰのモル比は、このようにして求めたＺｎとＰの原子濃度の比として求めることができる。
【００９２】
次に、上記表面処理皮膜の上部に第二層皮膜として形成される上層皮膜（有機皮膜）について説明する。
この上層皮膜は、樹脂組成物の主成分が、皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物からなり、皮膜厚が０．５〜２．０μｍの皮膜である。この上層皮膜もクロムを全く含まない。
【００９３】
皮膜形成有機樹脂（Ｅ）の種類としては、一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）と反応して、皮膜形成有機樹脂に活性水素含有化合物（Ｆ）が付加、縮合などの反応により結合でき、且つ皮膜を適切に形成できる樹脂であれば特別な制約はない。この皮膜形成有機樹脂（Ｅ）としては、例えば、エポキシ樹脂、変性エポキシ樹脂、ポリウレタン樹脂、ポリエステル樹脂、アルキド樹脂、アクリル系共重合体樹脂、ポリブタジエン樹脂、フェノール樹脂、およびこれらの樹脂の付加物または縮合物などを挙げることができ、これらのうちの１種を単独でまたは２種以上を混合して使用することができる。
【００９４】
また、皮膜形成有機樹脂（Ｅ）としては、反応性、反応の容易さ、防食性などの点から、樹脂中にエポキシ基を含有するエポキシ基含有樹脂（Ｈ）が特に好ましい。このエポキシ基含有樹脂（Ｈ）としては、一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）と反応して、皮膜形成有機樹脂に活性水素含有化合物（Ｆ）が付加、縮合などの反応により結合でき、且つ皮膜を適切に形成できる樹脂であれば特別な制約はなく、例えば、エポキシ樹脂、変性エポキシ樹脂、エポキシ基含有モノマーと共重合したアクリル系共重合体樹脂、エポキシ基を有するポリブタジエン樹脂、エポキシ基を有するポリウレタン樹脂、およびこれらの樹脂の付加物若しくは縮合物などが挙げられ、これらのエポキシ基含有樹脂の１種を単独でまたは２種以上混合して用いることができる。
また、これらのエポキシ基含有樹脂（Ｈ）の中でも、めっき表面との密着性、耐食性の点からエポキシ樹脂、変性エポキシ樹脂が特に好適である。またその中でも、酸素などの腐食因子に対して優れた遮断性を有する熱硬化性のエポキシ樹脂や変性エポキシ樹脂が最適であり、とりわけ高度な導電性及びスポット溶接性を得るために皮膜の付着量を低レベルにする場合には特に有利である。
【００９５】
上記エポキシ樹脂としては、ビスフェノールＡ、ビスフェノールＦ、ノボラック型フェノールなどのポリフェノール類とエピクロルヒドリンなどのエピハロヒドリンとを反応させてグリシジル基を導入してなるか、若しくはこのグリシジル基導入反応生成物にさらにポリフェノール類を反応させて分子量を増大させてなる芳香族エポキシ樹脂、さらには脂肪族エポキシ樹脂、脂環族エポキシ樹脂などが挙げられ、これらの１種を単独でまたは２種以上を混合して使用することができる。これらのエポキシ樹脂は、特に低温での皮膜形成性を必要とする場合には数平均分子量が１５００以上であることが好適である。
【００９６】
上記変性エポキシ樹脂としては、上記エポキシ樹脂中のエポキシ基または水酸基に各種変性剤を反応させた樹脂を挙げることができ、例えば、乾性油脂肪酸を反応させたエポキシエステル樹脂、アクリル酸またはメタクリル酸などを含有する重合性不飽和モノマー成分で変性したエポキシアクリレート樹脂、イソシアネート化合物を反応させたウレタン変性エポキシ樹脂などを例示できる。
【００９７】
上記エポキシ基含有モノマーと共重合したアクリル系共重合体樹脂としては、エポキシ基を有する不飽和モノマーとアクリル酸エステルまたはメタクリル酸エステルを必須とする重合性不飽和モノマー成分とを、溶液重合法、エマルション重合法または懸濁重合法などによって合成した樹脂を挙げることができる。
上記重合性不飽和モノマー成分としては、例えば、メチル（メタ）アクリレート、エチル（メタ）アクリレート、プロピル（メタ）アクリレート、ｎ−，ｉｓｏ−若しくはｔｅｒｔ−ブチル（メタ）アクリレート、ヘキシル（メタ）アクリレート、２−エチルヘキシル（メタ）アクリレート、デシル（メタ）アクリレート、ラウリル（メタ）アクリレートなどのアクリル酸又はメタクリル酸のＣ１〜２４アルキルエステル；アクリル酸、メタクリル酸、スチレン、ビニルトルエン、アクリルアミド、アクリロニトリル、Ｎ−メチロール（メタ）アクリルアミド、Ｎ−メチロール（メタ）アクリルアミドのＣ１〜４アルキルエーテル化物；Ｎ，Ｎ−ジエチルアミノエチルメタクリレートなどを挙げることができる。
【００９８】
また、エポキシ基を有する不飽和モノマーとしては、グリシジルメタクリレート、グリシジルアクリレート、３，４−エポキシシクロヘキシルメチル（メタ）アクリレートなど、エポキシ基と重合性不飽和基を持つものであれば特別な制約はない。
また、このエポキシ基含有モノマーと共重合したアクリル系共重合体樹脂は、ポリエステル樹脂、エポキシ樹脂、フェノール樹脂などによって変性させた樹脂とすることもできる。
【００９９】
前記エポキシ樹脂として特に好ましいのは、ビスフェノールＡとエピハロヒドリンとの反応生成物である下式に示される化学構造を有する樹脂であり、このエポキシ樹脂は特に耐食性に優れているため好ましい。
【化２】

このようなビスフェノールＡ型エポキシ樹脂の製造法は当業界において広く知られている。また、上記化学構造式において、ｑは０〜５０、好ましくは１〜４０、特に好ましくは２〜２０である。
なお、皮膜形成有機樹脂（Ｅ）は、有機溶剤溶解型、有機溶剤分散型、水溶解型、水分散型のいずれであってもよい。
【０１００】
本発明では皮膜形成有機樹脂（Ｅ）の分子中にヒドラジン誘導体を付与することを狙いとしており、このため活性水素含有化合物（Ｆ）の少なくとも一部（好ましくは全部）は、活性水素を有するヒドラジン誘導体（Ｇ）であることが必要である。
皮膜形成有機樹脂（Ｅ）がエポキシ基含有樹脂である場合、そのエポキシ基と反応する活性水素含有化合物（Ｆ）として例えば以下に示すようなものを例示でき、これらの１種または２種以上を使用できるが、この場合も活性水素含有化合物（Ｆ）の少なくとも一部（好ましくは全部）は、活性水素を有するヒドラジン誘導体であることが必要である。
・活性水素を有するヒドラジン誘導体
・活性水素を有する第１級または第２級のアミン化合物
・アンモニア、カルボン酸などの有機酸
・塩化水素などのハロゲン化水素
・アルコール類、チオール類
・活性水素を有しないヒドラジン誘導体または第３級アミンと酸との混合物である４級塩化剤
【０１０１】
前記活性水素を有するヒドラジン誘導体（Ｇ）としては、例えば、以下のものを挙げることができる。
▲１▼ カルボヒドラジド、プロピオン酸ヒドラジド、サリチル酸ヒドラジド、アジピン酸ジヒドラジド、セバシン酸ジヒドラジド、ドデカン酸ジヒドラジド、イソフタル酸ジヒドラジド、チオカルボヒドラジド、４，４′−オキシビスベンゼンスルホニルヒドラジド、ベンゾフェノンヒドラゾン、アミノポリアクリルアミドなどのヒドラジド化合物；
▲２▼ ピラゾール、３，５−ジメチルピラゾール、３−メチル−５−ピラゾロン、３−アミノ−５−メチルピラゾールなどのピラゾール化合物；
【０１０２】
▲３▼ １，２，４−トリアゾール、３−アミノ−１，２，４−トリアゾール、４−アミノ−１，２，４−トリアゾール、３−メルカプト−１，２，４−トリアゾール、５−アミノ−３−メルカプト−１，２，４−トリアゾール、２，３−ジヒドロ−３−オキソ−１，２，４−トリアゾール、１Ｈ−ベンゾトリアゾール、１−ヒドロキシベンゾトリアゾール（１水和物）、６−メチル−８−ヒドロキシトリアゾロピリダジン、６−フェニル−８−ヒドロキシトリアゾロピリダジン、５−ヒドロキシ−７−メチル−１，３，８−トリアザインドリジンなどのトリアゾール化合物；
【０１０３】
▲４▼ ５−フェニル−１，２，３，４−テトラゾール、５−メルカプト−１−フェニル−１，２，３，４−テトラゾールなどのテトラゾール化合物；
▲５▼ ５−アミノ−２−メルカプト−１，３，４−チアジアゾール、２，５−ジメルカプト−１，３，４−チアジアゾールなどのチアジアゾール化合物；
▲６▼ マレイン酸ヒドラジド、６−メチル−３−ピリダゾン、４，５−ジクロロ−３−ピリダゾン、４，５−ジブロモ−３−ピリダゾン、６−メチル−４，５−ジヒドロ−３−ピリダゾンなどのピリダジン化合物
【０１０４】
また、これらのなかでも、５員環または６員環の環状構造を有し、環状構造中に窒素原子を有するピラゾール化合物、トリアゾール化合物が特に好適である。これらのヒドラジン誘導体は１種を単独でまたは２種以上を混合して使用することができる。
【０１０５】
活性水素含有化合物（Ｆ）の一部として使用できる上記活性水素を有するアミン化合物の代表例としては、例えば、以下のものを挙げることができる。
▲１▼ ジエチレントリアミン、ヒドロキシエチルアミノエチルアミン、エチルアミノエチルアミン、メチルアミノプロピルアミンなどの１個の２級アミノ基と１個以上の１級アミノ基を含有するアミン化合物の１級アミノ基を、ケトン、アルデヒド若しくはカルボン酸と例えば１００〜２３０℃程度の温度で加熱反応させてアルジミン、ケチミン、オキサゾリン若しくはイミダゾリンに変性した化合物；
【０１０６】
▲２▼ ジエチルアミン、ジエタノールアミン、ジ−ｎ−または−ｉｓｏ−プロパノールアミン、Ｎ−メチルエタノールアミン、Ｎ−エチルエタノールアミンなどの第２級モノアミン；
▲３▼ モノエタノールアミンのようなモノアルカノールアミンとジアルキル（メタ）アクリルアミドとをミカエル付加反応により付加させて得られた第２級アミン含有化合物；
▲４▼ モノエタノールアミン、ネオペンタノールアミン、２−アミノプロパノール、３−アミノプロパノール、２−ヒドロキシ−２′（アミノプロポキシ）エチルエーテルなどのアルカノールアミンの１級アミノ基をケチミンに変性した化合物；
【０１０７】
活性水素含有化合物（Ｆ）の一部として使用できる上記４級塩化剤は、活性水素を有しないヒドラジン誘導体または第３級アミンはそれ自体ではエポキシ基と反応性を有しないので、これらをエポキシ基と反応可能とするために酸との混合物としたものである。４級塩化剤は、必要に応じて水の存在下でエポキシ基と反応し、エポキシ基含有樹脂と４級塩を形成する。
４級塩化剤を得るために使用される酸は、酢酸、乳酸などの有機酸、塩酸などの無機酸のいずれでもよい。また、４級塩化剤を得るために使用される活性水素を有しないヒドラジン誘導体としては、例えば３，６−ジクロロピリダジンなどを、また、第３級アミンとしては、例えば、ジメチルエタノールアミン、トリエチルアミン、トリメチルアミン、トリイソプロピルアミン、メチルジエタノールアミンなどを挙げることができる。
【０１０８】
皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物は、皮膜形成有機樹脂（Ｅ）と活性水素含有化合物（Ｆ）とを１０〜３００℃、好ましくは５０〜１５０℃で約１〜８時間程度反応させて得られる。
この反応は有機溶剤を加えて行ってもよく、使用する有機溶剤の種類は特に限定されない。例えば、アセトン、メチルエチルケトン、メチルイソブチルケトン、ジブチルケトン、シクロヘキサノンなどのケトン類；エタノール、ブタノール、２−エチルヘキシルアルコール、ベンジルアルコール、エチレングリコール、エチレングリコールモノイソプロピルエーテル、エチレングリコールモノブチルエーテル、エチレングリコールモノヘキシルエーテル、プロピレングリコール、プロピレングリコールモノメチルエーテル、ジエチレングリコール、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノブチルエーテルなどの水酸基を含有するアルコール類やエーテル類；酢酸エチル、酢酸ブチル、エチレングリコールモノブチルエーテルアセテートなどのエステル類；トルエン、キシレンなどの芳香族炭化水素などを例示でき、これらの１種又は２種以上を使用することができる。また、これらのなかでエポキシ樹脂との溶解性、塗膜形成性などの面からは、ケトン系またはエーテル系の溶剤が特に好ましい。
【０１０９】
皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との配合比率は、固形分の割合で皮膜形成有機樹脂（Ｅ）１００質量部に対して、活性水素含有化合物（Ｆ）を０．５〜２０質量部、特に好ましくは１．０〜１０質量部とするのが望ましい。
また、皮膜形成有機樹脂（Ｅ）がエポキシ基含有樹脂（Ｈ）である場合には、エポキシ基含有樹脂（Ｈ）と活性水素含有化合物（Ｆ）との配合比率は、活性水素含有化合物（Ｆ）の活性水素基の数とエポキシ基含有樹脂（Ｈ）のエポキシ基の数との比率［活性水素基数／エポキシ基数］が０．０１〜１０、より好ましくは０．１〜８、さらに好ましくは０．２〜４とすることが耐食性などの点から適当である。
【０１１０】
また、活性水素含有化合物（Ｆ）中における活性水素を有するヒドラジン誘導体（Ｇ）の割合は１０〜１００モル％、より好ましくは３０〜１００モル％、さら好ましくは４０〜１００モル％とすることが適当である。活性水素を有するヒドラジン誘導体（Ｇ）の割合が１０モル％未満では有機皮膜に十分な防錆機能を付与することができず、得られる防錆効果は皮膜形成有機樹脂とヒドラジン誘導体を単に混合して使用した場合と大差なくなる。
【０１１１】
本発明では緻密なバリヤー皮膜を形成するために、樹脂組成物中に硬化剤を配合し、有機皮膜（上層皮膜）を加熱硬化させることが望ましい。
樹脂組成物皮膜を形成する場合の硬化方法としては、(1)イソシアネートと基体樹脂中の水酸基とのウレタン化反応を利用する硬化方法、(2)メラミン、尿素およびベンゾグアナミンの中から選ばれた１種以上にホルムアルデヒドを反応させてなるメチロール化合物の一部若しくは全部に炭素数１〜５の１価アルコールを反応させてなるアルキルエーテル化アミノ樹脂と基体樹脂中の水酸基との間のエーテル化反応を利用する硬化方法、が適当であるが、このうちイソシアネートと基体樹脂中の水酸基とのウレタン化反応を主反応とすることが特に好適である。
【０１１２】
上記(1)の硬化方法で用いるポリイソシアネート化合物は、１分子中に少なくとも２個のイソシアネート基を有する脂肪族、脂環族（複素環を含む）または芳香族イソシアネート化合物、若しくはそれらの化合物を多価アルコールで部分反応させた化合物である。このようなポリイソシアネート化合物としては、例えば以下のものが例示できる。
▲１▼ ｍ−またはｐ−フェニレンジイソシアネート、２，４−または２，６−トリレンジイソシアネート、ｏ−またはｐ−キシリレンジイソシアネート、ヘキサメチレンジイソシアネート、ダイマー酸ジイソシアネート、イソホロンジイソシアネート
【０１１３】
▲２▼ 上記▲１▼の化合物単独またはそれらの混合物と多価アルコール（エチレングリコール、プロピレングリコールなどの２価アルコール類；グリセリン、トリメチロールプロパンなどの３価アルコール；ペンタエリスリトールなどの４価アルコール；ソルビトール、ジペンタエリスリトールなどの６価アルコールなど）との反応生成物であって、１分子中に少なくとも２個のイソシアネートが残存する化合物
これらのポリイソシアネート化合物は、１種を単独で、または２種以上を混合して使用できる。
【０１１４】
また、ポリイソシアネート化合物の保護剤（ブロック剤）としては、例えば、
▲１▼ メタノール、エタノール、プロパノール、ブタノール、オクチルアルコールなどの脂肪族モノアルコール類
▲２▼ エチレングリコールおよび／またはジエチレングリコールのモノエーテル類、例えば、メチル、エチル、プロピル（ｎ−，ｉｓｏ）、ブチル（ｎ−，ｉｓｏ，ｓｅｃ）などのモノエーテル
▲３▼ フェノール、クレゾールなどの芳香族アルコール
▲４▼ アセトオキシム、メチルエチルケトンオキシムなどのオキシム
などが使用でき、これらの１種または２種以上と前記ポリイソシアネート化合物とを反応させることにより、少なくとも常温下で安定に保護されたポリイソシアネート化合物を得ることができる。
【０１１５】
このようなポリイソシアネート化合物（Ｉ）は、硬化剤として皮膜形成有機樹脂（Ｅ）に対し、（Ｅ）／（Ｉ）＝９５／５〜５５／４５（不揮発分の重量比）、好ましくは（Ｅ）／（Ｉ）＝９０／１０〜６５／３５の割合で配合するのが適当である。ポリイソシアネート化合物には吸水性があり、これを（Ｅ）／（Ｉ）＝５５／４５を超えて配合すると上層皮膜の密着性を劣化させてしまう。さらに、上層皮膜上に上塗り塗装を行った場合、未反応のポリイソシアネート化合物が塗膜中に移動し、塗膜の硬化阻害や密着性不良を起こしてしまう。このような観点から、ポリイソシアネート化合物（Ｉ）の配合量は（Ｅ）／（Ｉ）＝５５／４５以下とすることが好ましい。
【０１１６】
なお、皮膜形成有機樹脂（Ｅ）は以上のような架橋剤（硬化剤）の添加により十分に架橋するが、さらに低温架橋性を増大させるため、公知の硬化促進触媒を使用することが望ましい。この硬化促進触媒としては、例えば、Ｎ−エチルモルホリン、ジブチル錫ジラウレート、ナフテン酸コバルト、塩化第１スズ、ナフテン酸亜鉛、硝酸ビスマスなどが使用できる。
また、例えば皮膜形成有機樹脂（Ｅ）にエポキシ基含有樹脂を使用する場合、付着性など若干の物性向上を狙いとして、エポキシ基含有樹脂とともに公知のアクリル、アルキッド、ポリエステルなどの樹脂を混合して用いることもできる。
【０１１７】
上層皮膜には、耐食性向上を目的として、必要に応じて非クロム系防錆添加剤を含有させることができる。上層皮膜中にこのような非クロム系防錆添加剤を含有させることにより、より優れた防食性能を得ることができる。
この非クロム系防錆添加剤は特に下記（ｅ１）〜（ｅ５）の中から選ばれる１つ以上を用いることが好ましい。
（ｅ１）酸化ケイ素
（ｅ２）カルシウム又はカルシウム化合物
（ｅ３）難溶性リン酸化合物
（ｅ４）モリブデン酸化合物
（ｅ５）トリアゾール類、チオール類、チアジアゾール類、チアゾール類、チウラム類の中から選ばれる１種以上の、Ｓ原子を含有する有機化合物
これら（ｅ１）〜（ｅ５）の非クロム系防錆添加剤の詳細および防食機構は、先に表面処理皮膜に関して述べた通りである。
【０１１８】
非クロム系防錆添加剤の配合量は、皮膜形成用の樹脂組成物の固形分１００質量部に対して、固形分の割合で０．1〜５０質量部、好ましくは０．５〜３０質量部とするのが適当である。この非クロム系防錆添加剤の配合量が０．１質量部未満では、耐アルカリ脱脂後の耐食性向上効果が十分に得られず、一方、５０質量部を超えると塗装性、加工性および溶接性が低下するだけでなく、耐食性も低下するので好ましくない。
なお、上記（ｅ1）〜（ｅ5）の防錆添加剤を２種以上複合添加してもよく、この場合にはそれぞれ固有の防食作用が複合化されるため、より高度の耐食性が得られる。特に、上記（ｅ1）の成分としてカルシウムイオン交換シリカを用い、且つこれに（ｅ3）、（ｅ4）、（ｅ5）の成分の１種以上、特に好ましくは（ｅ3）〜（ｅ5）の成分の全部を複合添加した場合に特に優れた耐食性が得られる。
【０１１９】
また、上層皮膜中には上記の防錆添加成分に加えて、腐食抑制剤として、他の酸化物微粒子（例えば、酸化アルミニウム、酸化ジルコニウム、酸化チタン、酸化セリウム、酸化アンチモンなど）、リンモリブデン酸塩（例えば、リンモリブデン酸アルミニウムなど）、有機リン酸及びその塩（例えば、フィチン酸、フィチン酸塩、ホスホン酸、ホスホン酸塩、及びこれらの金属塩、アルカリ金属塩、アルカリ土類金属塩など）、有機インヒビター（例えば、ヒドラジン誘導体、チオール化合物、ジチオカルバミン酸塩など）などの１種又は２種以上を添加できる。
【０１２０】
上層皮膜中には、さらに必要に応じて、皮膜の加工性を向上させる目的で固形潤滑剤を配合することができる。
本発明に適用できる固形潤滑剤としては、例えば、以下のようなものが挙げられ、これらの１種または２種以上を用いることができる。。
（１）ポリオレフィンワックス、パラフィンワックス：例えば、ポリエチレンワックス、合成パラフィン、天然パラフィン、マイクロワックス、塩素化炭化水素など
（２）フッ素樹脂微粒子：例えば、ポリフルオロエチレン樹脂（ポリ４フッ化エチレン樹脂など）、ポリフッ化ビニル樹脂、ポリフッ化ビニリデン樹脂など
【０１２１】
また、この他にも、脂肪酸アミド系化合物（例えば、ステアリン酸アミド、パルミチン酸アミド、メチレンビスステアロアミド、エチレンビスステアロアミド、オレイン酸アミド、エシル酸アミド、アルキレンビス脂肪酸アミドなど）、金属石けん類（例えば、ステアリン酸カルシウム、ステアリン酸鉛、ラウリン酸カルシウム、パルミチン酸カルシウムなど）、金属硫化物（例えば、二硫化モリブデン、二硫化タングステンなど）、グラファイト、フッ化黒鉛、窒化ホウ素、ポリアルキレングリコール、アルカリ金属硫酸塩などの１種または２種以上を用いてもよい。
【０１２２】
以上の固形潤滑剤の中でも、特に、ポリエチレンワックス、フッ素樹脂微粒子（なかでも、ポリ４フッ化エチレン樹脂微粒子）が好適である。
ポリエチレンワックスとしては、例えば、ヘキスト社製のセリダスト ９６１５Ａ、セリダスト ３７１５、セリダスト ３６２０、セリダスト ３９１０（いずれも商品名）、三洋化成（株）製のサンワックス １３１−Ｐ、サンワックス １６１−Ｐ（いずれも商品名）、三井石油化学（株）製のケミパール Ｗ−１００、ケミパール Ｗ−２００、ケミパール Ｗ−５００、ケミパール Ｗ−８００、ケミパール Ｗ−９５０（いずれも商品名）などを用いることができる。
【０１２３】
また、フッ素樹脂微粒子としては、テトラフルオロエチレン微粒子が最も好ましく、例えば、ダイキン工業（株）製のルブロン Ｌ−２、ルブロン Ｌ−５（いずれも商品名）、三井・デュポン（株）製のＭＰ１１００、ＭＰ１２００（いずれも商品名）、旭アイシーアイフロロポリマーズ（株）製のフルオンディスパージョン ＡＤ１、フルオンディスパージョン ＡＤ２、フルオン Ｌ１４１Ｊ、フルオン Ｌ１５０Ｊ、フルオン Ｌ１５５Ｊ（いずれも商品名）などが好適である。
また、これらのなかで、ポリオレフィンワックスとテトラフルオロエチレン微粒子の併用により特に優れた潤滑効果が期待できる。
【０１２４】
上層皮膜中での固形潤滑剤の配合量は、皮膜形成用の樹脂組成物１００質量部（固形分）に対して、１〜３０質量部（固形分）、好ましくは１〜１０質量部（固形分）とする。固形潤滑剤の配合量が１質量部未満では潤滑効果が乏しく、一方、配合量が３０質量部を超えると塗装性が低下するので好ましくない。
【０１２５】
本発明の表面処理鋼板が有する上層皮膜は、皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物（樹脂組成物）を主成分とし、これに必要に応じて硬化剤、非クロム系防錆添加剤、固形潤滑剤などが添加されるが、さらに必要に応じて、添加剤として、有機着色顔料（例えば、縮合多環系有機顔料、フタロシアニン系有機顔料など）、着色染料（例えば、有機溶剤可溶性アゾ系染料、水溶性アゾ系金属染料など）、無機顔料（例えば、酸化チタンなど）、キレート剤（例えば、チオールなど）、導電性顔料（例えば、亜鉛、アルミニウム、ニッケルなどの金属粉末、リン化鉄、アンチモンドープ型酸化錫など）、カップリング剤（例えば、シランカップリング剤、チタンカップリング剤など）、メラミン・シアヌル酸付加物などの１種又は２種以上を添加することができる。
【０１２６】
また、上記主成分および添加成分を含む皮膜形成用の塗料組成物は、通常、溶媒（有機溶剤および／または水）を含有し、さらに必要に応じて中和剤などが添加される。
上記有機溶剤としては、上記皮膜形成有機樹脂（Ｅ）と活性水素含有化合物（Ｆ）との反応生成物を溶解または分散でき、塗料組成物として調整できるものであれば特別な制約なく、例えば、先に例示した種々の有機溶剤を使用することができる。
上記中和剤は、皮膜形成有機樹脂（Ｅ）を中和して水性化するために必要に応じて配合されるものであり、皮膜形成有機樹脂（Ｅ）がカチオン性樹脂である場合には酢酸、乳酸、蟻酸などの酸を中和剤として使用することができる。
上層皮膜の乾燥膜厚は０．５〜２．０μｍ、好ましくは０．５〜１．５μｍとする。上層皮膜の膜圧が０．５μｍ未満では耐食性が不十分であり、一方、膜厚が２．０μｍを超えると溶接性や電着塗装性が低下する。
また、溶接性や電着塗装性の観点からは、第一層の表面処理皮膜と第二層の上層皮膜の合計膜厚は２．０μｍ以下であることが好ましい。
【０１２７】
次に、本発明の表面処理鋼板の製造方法について説明する。
亜鉛系めっき鋼板またはアルミニウム系めっき鋼板の表面に上記表面処理皮膜を形成するには、上述した組成を有する表面処理組成物（処理液）を乾燥皮膜厚が上記範囲となるようにめっき鋼板面に塗布し、水洗することなく加熱乾燥させる。
【０１２８】
表面処理組成物をめっき鋼板面に形成する方法としては、塗布法、浸漬法、スプレー法のいずれでもよい。塗布処理方法としては、ロールコーター（３ロール方式、２ロール方式など）、スクイズコーター、ダイコーターなどいずれの方法でもよい。また、スクイズコーターなどによる塗布処理または浸漬処理、スプレー処理の後に、エアナイフ法やロール絞り法により塗布量の調整、外観の均一化、膜厚の均一化を行うことも可能である。
【０１２９】
表面処理組成物をコーティングした後は、水洗することなく加熱乾燥を行う。加熱乾燥手段としては、ドライヤー、熱風炉、高周波誘導加熱炉、赤外線炉などを用いることができる。加熱乾燥は到達板温で３０〜１５０℃、好ましくは４０℃〜１４０℃の範囲で行うことが望ましい。この加熱乾燥温度が３０℃未満では皮膜中に水分が多量に残り、耐食性が不十分となる。また、加熱乾燥温度が１５０℃を超えると非経済的であるばかりでなく、皮膜に欠陥が生じ耐食性が低下する。また、加熱乾燥温度が１５０℃を超えるとＢＨ鋼板に適用できなくなるため好ましくない。
上記のようにして形成された表面処理皮膜の上層には、第二層皮膜として上層皮膜（有機樹脂皮膜）を形成する。第二層皮膜用の塗料組成物を上述した膜厚となるよう上記表面処理皮膜面に塗布し、加熱乾燥させる。塗料組成物の塗布は、上述した表面処理皮膜の形成に用いた方法に準じて行えばよい。
【０１３０】
塗料組成物の塗布後、通常は水洗することなく、加熱乾燥を行うが、塗料組成物の塗布後に水洗工程を実施しても構わない。加熱乾燥処理には、ドライヤー、熱風炉、高周波誘導加熱炉、赤外線炉などを用いることができる。加熱乾燥は到達板温で３０〜１５０℃、好ましくは４０℃〜１４０℃の範囲で行うことが望ましい。この加熱乾燥温度が３０℃未満では皮膜中に水分が多量に残り、耐食性が不十分となる。また、加熱乾燥温度が１５０℃を超えると非経済的であるばかりでなく、皮膜に欠陥が生じ耐食性が低下する。また、加熱乾燥温度が１５０℃を超えるとＢＨ鋼板に適用できなくなるため好ましくない。
【０１３１】
したがって、本発明の表面処理鋼板の製造方法およびその好ましい実施形態は以下のとおりである。
[1] 亜鉛系めっき鋼板またはアルミニウム系めっき鋼板の表面に、下記成分（ａ）〜（ｃ）を含有する表面処理組成物を塗布し、到達板温が３０〜１５０℃の温度で乾燥することにより皮膜厚が０．０１〜１．０μｍの表面処理皮膜を形成し、
（ａ）数平均分子量４００〜２００００のポリアルキレングリコール、ビスフェノール型エポキシ樹脂、活性水素含有化合物及びポリイソシアネート化合物を反応させて得られたポリアルキレングリコール変性エポキシ樹脂（Ａ）と、該ポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）とを反応させて得られた樹脂を水に分散させてなる水性エポキシ樹脂分散液
（ｂ）シランカップリング剤：前記水性エポキシ樹脂分散液の固形分１００質量部に対して１〜３００質量部
（ｃ）リン酸および／またはヘキサフルオロ金属酸：前記水性エポキシ樹脂分散液の固形分１００質量部に対して０．１〜８０質量部
その上層に、樹脂組成物の主成分が、皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物からなる塗料組成物を塗布し、到達板温が３０〜１５０℃の温度で乾燥することにより皮膜厚が０．５〜２．０μｍの上層皮膜を形成することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３２】
[2] 亜鉛系めっき鋼板またはアルミニウム系めっき鋼板の表面に、下記成分（ａ）〜（ｃ）を含有する表面処理組成物を塗布し、到達板温が３０〜１５０℃の温度で乾燥することにより皮膜厚が０．０１〜１．０μｍの表面処理皮膜を形成し、
（ａ）数平均分子量４００〜２００００のポリアルキレングリコール、ビスフェノール型エポキシ樹脂、活性水素含有化合物及びポリイソシアネート化合物を反応させて得られたポリアルキレングリコール変性エポキシ樹脂（Ａ）と、該ポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）と、該ヒドラジン誘導体（Ｃ）以外の活性水素含有化合物（Ｄ）とを反応させて得られた樹脂を水に分散させてなる水性エポキシ樹脂分散液
（ｂ）シランカップリング剤：前記水性エポキシ樹脂分散液の固形分１００質量部に対して１〜３００質量部
（ｃ）リン酸および／またはヘキサフルオロ金属酸：前記水性エポキシ樹脂分散液の固形分１００質量部に対して０．１〜８０質量部
その上層に、樹脂組成物の主成分が、皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物からなる塗料組成物を塗布し、到達板温が３０〜１５０℃の温度で乾燥することにより皮膜厚が０．５〜２．０μｍの上層皮膜を形成することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３３】
[3] 上記[1]または[2]の製造方法において、成分（ａ）の水性エポキシ樹脂分散液を得るためのエポキシ基含有樹脂（Ｂ）が、エポキシ当量１５０〜５０００のビスフェノールＡ型エポキシ樹脂であり、その数平均分子量が１５００〜１００００であることを特徴とする高耐食性表面処理鋼板の製造方法。
[4] 上記[1]〜[3]のいずれかの製造方法において、成分（ａ）の水性エポキシ樹脂分散液がさらに、水酸基と架橋する基を有する硬化剤を含有することを特徴とする高耐食性表面処理鋼板の製造方法。
[5] 上記[1]〜[4]のいずれかの製造方法において、表面処理皮膜形成用の表面処理組成物がさらに、水溶性リン酸塩を、成分（ａ）の水性エポキシ樹脂分散液の固形分１００質量部に対して固形分の割合で０．１〜６０質量部含有することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３４】
[6] 上記[5]の製造方法において、表面処理皮膜形成用の表面処理組成物が水溶性リン酸塩として、カチオン成分とＰ_２Ｏ_５成分のモル比［カチオン］／［Ｐ_２Ｏ_５］が０．４〜１．０であって、且つカチオン種がＭｎ、Ｍｇ、Ａｌ、Ｎｉの中から選ばれる１種以上である水溶性リン酸塩を含有することを特徴とする高耐食性表面処理鋼板の製造方法。
[7] 上記[1]〜[6]のいずれかの製造方法において、表面処理皮膜形成用の表面処理組成物がさらに、非クロム系防錆添加剤を、成分（ａ）の水性エポキシ樹脂分散液の固形分１００質量部に対して固形分の割合で０．１〜５０質量部含有することを特徴とする高耐食性表面処理鋼板の製造方法。
[8] 上記[1]〜[7]のいずれかの製造方法において、上層皮膜形成用の塗料組成物がさらに、非クロム系防錆添加剤を、樹脂組成物の固形分１００質量部に対して固形分の割合で０．１〜５０質量部含有することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３５】
[9] 上記[7]または[8]の製造方法において、表面処理皮膜形成用の表面処理組成物および／または上層皮膜形成用の塗料組成物が、非クロム系防錆添加剤として、下記（ｅ1）〜（ｅ5）の中から選ばれる１つ以上の防錆添加剤を含有することを特徴とする高耐食性表面処理鋼板の製造方法。
（ｅ1）酸化ケイ素
（ｅ2）カルシウムおよび／またはカルシウム化合物
（ｅ3）難溶性リン酸化合物
（ｅ4）モリブデン酸化合物
（ｅ5）トリアゾール類、チオール類、チアジアゾール類、チアゾール類、チウラム類の中から選ばれる１種以上の、Ｓ原子を含有する有機化合物
[10] 上記[1]〜[9]のいずれかの製造方法において、成分（ｂ）のシランカップリング剤として、反応性官能基としてアミノ基を有するシランカップリング剤の少なくとも１種を含有することを特徴とする高耐食性表面処理鋼板の製造方法。 [11] 上記[1]〜[10]のいずれかの製造方法において、上層皮膜形成用の塗料組成物がさらに、固形潤滑剤を、樹脂組成物の固形分１００質量部に対して固形分の割合で１〜３０質量部含有することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３６】
なお、上述した表面処理皮膜及び上層皮膜はめっき鋼板の片面、両面のいずれに形成してもよく、めっき鋼板表裏面の皮膜形態の組み合わせとしては、例えば、表面処理皮膜＋上層皮膜／無処理、表面処理皮膜＋上層皮膜／表面処理皮膜、表面処理皮膜＋上層皮膜／表面処理皮膜＋上層皮膜など、任意の形態とすることができる。
【０１３７】
【実施例】
[実施例１]
第一層形成用の表面処理組成物は、樹脂組成物として表２に示す水溶性または水分散性エポキシ樹脂を用い、これにシランカップリング剤（表３）、リン酸又はヘキサフルオロ金属酸（表４）、水溶性リン酸塩（表５）、非クロム系防錆添加剤（表６）を適宜配合し、塗料用分散機（サンドグラインダー）を用いて所定時間攪拌し、表面処理組成物を調製した。
表２に示す水溶性または水分散性エポキシ樹脂は以下のようにして製造した。・ポリアルキレングリコール変性エポキシ樹脂の製造
＜製造例１＞
温度計、撹拌機、冷却管を備えたガラス製四つ口フラスコに、数平均分子量４０００のポリエチレングリコール１６８８ｇとメチルエチルケトン５３９ｇ加え、６０℃で撹拌混合し均一透明になった後、トリレンジイソシアネート１７１ｇを加え、２時間反応させた後、エピコート８３４Ｘ９０（エポキシ樹脂，シェルジャパン社製、エポキシ当量２５０）１１２１ｇ、ジエチレングリコーリエチルエーテル６６ｇおよび１％ジブチルチンジラウレート溶液１．１gを添加し、さらに２時間反応させた。その後８０℃まで昇温し、３時間反応させてイソシアネート価が０．６以下になったことを確認した。その後９０℃まで昇温し、減圧蒸留により固形分濃度が８１．７％になるまでメチルエチルケトンを除去した。除去後、プロピレングリコールモノメチルエーテル６５９ｇ、脱イオン水２７０ｇを加えて希釈し、固形分濃度７６％のポリアルキレングリコール変性エポキシ樹脂溶液Ａ１を得た。
【０１３８】
・水性エポキシ樹脂分散液の製造
＜製造例２＞
ＥＰ１００４（エポキシ樹脂，油化シェルエポキシ社製，エポキシ当量１０００）２０２９ｇとプロピレングリコールモノブチルエーテル６９７ｇを四つ口フラスコに仕込み、１１０℃まで昇温して１時間で完全にエポキシ樹脂を溶解した。このものに、製造例１で得たポリアルキレングリコール変性エポキシ樹脂溶液Ａ１を１１８０ｇおよび３−アミノ−１，２，４−トリアゾール（分子量８４）３１１．７ｇ加えて１００℃で５時間反応させた後、プロピレングリコールモノブチルエーテル７１９．６ｇを加えて樹脂溶液Ｄ１を得た。
上記樹脂溶液Ｄ１を２５７．６ｇにＭＦ−Ｋ６０Ｘ（イソシアネート硬化剤，旭化成工業社製）５０ｇおよびＳｃａｔ２４（硬化触媒）０．３ｇを混合し、よく攪拌した後、水６９２．１ｇを少しずつ滴下・混合撹拌し、水性エポキシ樹脂分散液Ｅ１を得た。
【０１３９】
＜製造例３＞（ヒドラジン誘導体を含有しない水性エポキシ樹脂分散液）
ＥＰ１００４（エポキシ樹脂，油化シェルエポキシ社製，エポキシ当量１０００）２０２９ｇとプロピレングリコールモノブチルエーテル６９７ｇを四つ口フラスコに仕込み、１１０℃まで昇温して１時間で完全にエポキシ樹脂を溶解した。このものに、製造例１で得たポリアルキレングリコール変性エポキシ樹脂溶液Ａ１を１１８０ｇおよびプロピレングリコールモノブチルエーテル５２７．０ｇを加えて樹脂溶液Ｄ２を得た。
上記樹脂溶液Ｄ２を２５７．６ｇにＭＦ−Ｋ６０Ｘ（イソシアネート硬化剤，旭化成工業社製）５０ｇおよびＳｃａｔ２４（硬化触媒）０．３ｇを混合しよく攪拌した後、水６９２．１ｇを少しずつ滴下・混合撹拌し、水性エポキシ樹脂分散液Ｅ２を得た。
【０１４０】
第二層形成用の塗料組成物は、樹脂組成物として表７に示すものを用い、これに非クロム系防錆添加剤（表６）、固形潤滑剤（表８）を適宜配合し、塗料用分散機（サンドグラインダー）を用いて所定時間攪拌し、塗料組成物を調製した。表７に示す樹脂組成物の基体樹脂（反応生成物）は以下のようにして合成した。
＜合成例１＞
ＥＰ８２８（油化シェルエポキシ社製，エポキシ当量１８７）１８７０部とビスフェノールＡ９１２部、テトラエチルアンモニウムブロマイド２部、メチルイソブチルケトン３００部を四つ口フラスコに仕込み、１４０℃まで昇温して４時間反応させ、エポキシ当量１３９１、固形分９０％のエポキシ樹脂を得た。このものに、エチレングリコールモノブチルエーテル１５００部を加えてから１００℃に冷却し、３，５−ジメチルピラゾール（分子量９６）を９６部とジブチルアミン（分子量１２９）を１２９部加えて、エポキシ基が消失するまで６時間反応させた後、冷却しながらメチルイソブチルケトン２０５部を加えて、固形分６０％のピラゾール変性エポキシ樹脂を得た。これを樹脂組成物（１）とする。この樹脂組成物（１）は、皮膜形成有機樹脂（Ｅ）と、活性水素を有するヒドラジン誘導体（Ｇ）を５０ｍｏｌ％含む活性水素含有化合物との反応生成物である。
【０１４１】
＜合成例２＞
ＥＰ１００７（油化シェルエポキシ社製，エポキシ当量２０００）４０００部とエチレングリコールモノブチルエーテル２２３９部を四つ口フラスコに仕込み、１２０℃まで昇温して１時間で完全にエポキシ樹脂を溶解した。このものを１００℃に冷却し、３−アミノ−１，２，４−トリアゾール（分子量８４）を１６８部加えて、エポキシ基が消失するまで６時間反応させた後、冷却しながらメチルイソブチルケトン５４０部を加えて、固形分６０％のトリアゾール変成エポキシ樹脂を得た。これを樹脂組成物（２）とする。この樹脂組成物（２）は、皮膜形成有機樹脂（Ｅ）と、活性水素を有するヒドラジン誘導体（Ｇ）を１００ｍｏｌ％含む活性水素含有化合物との反応生成物である。
【０１４２】
＜合成例３＞
イソホロンジイソシアネート（イソシアネート当量１１１）２２２部とメチルイソブチルケトン３４部を四つ口フラスコに仕込み、３０〜４０℃に保ってメチルエチルケトキシム（分子量８７）８７部を３時間かけて滴下後、４０℃に２時間保ち、イソシアネート当量３０９、固形分９０％の部分ブロックイソシアネートを得た。
次いで、ＥＰ８２８（油化シェルエポキシ社製、エポキシ当量１８７）１４９６部とビスフェノールＡ６８４部、テトラエチルアンモニウムブロマイド１部、メチルイソブチルケトン２４１部を四つ口フラスコに仕込み、１４０℃まで昇温して４時間反応させ、エポキシ当量１０９０、固形分９０％のエポキシ樹脂を得た。このものに、メチルイソブチルケトン１０００部を加えてから１００℃に冷却し、３−メルカプト−１，２，４−トリアゾール（分子量１０１）を２０２部加えて、エポキシ基が消失するまで６時間反応させた後、上記固形分９０％の部分ブロックイソシアネートを２３０部加え１００℃で３時間反応させ、イソシアネート基が消失したことを確認した。さらに、エチレングリコールモノブチルエーテル４６１部を加えて、固形分６０％のトリアゾール変成エポキシ樹脂を得た。これを樹脂組成物（３）とする。この樹脂組成物（３）は、皮膜形成有機樹脂（Ｅ）と、活性水素を有するヒドラジン誘導体（Ｇ）を１００ｍｏｌ％含む活性水素含有化合物との反応生成物である。
【０１４３】
＜合成例４＞
ＥＰ８２８（油化シェルエポキシ社製、エポキシ当量１８７）１８７０部とビスフェノールＡ９１２部、テトラエチルアンモニウムブロマイド２部、メチルイソブチルケトン３００部を四つ口フラスコに仕込み、１４０℃まで昇温して４時間反応させ、エポキシ当量１３９１、固形分９０％のエポキシ樹脂を得た。このものに、エチレングリコールモノブチルエーテル１５００部を加えてから１００℃に冷却し、ジブチルアミン（分子量１２９）を２５８部加えて、エポキシ基が消失するまで６時間反応させた後、冷却しながらメチルイソブチルケトン２２５部を加えて、固形分６０％のエポキシアミン付加物を得た。これを樹脂組成物（４）とする。この樹脂組成物（４）は、皮膜形成有機樹脂（Ｅ）と、活性水素を有するヒドラジン誘導体（Ｇ）を含まない活性水素含有化合物との反応生成物である。
【０１４４】
冷延鋼板をベースとした家電、建材、自動車部品用のめっき鋼板である、表１に示すめっき鋼板を処理原板として用いた。なお、鋼板の板厚は評価の目的に応じて所定の板厚のものを採用した。このめっき鋼板の表面をアルカリ脱脂処理、水洗乾燥した後、上記第一層形成用の表面処理組成物をロールコーターにより塗布し、各種温度で加熱乾燥した。皮膜の膜厚は、表面処理組成物の固形分（加熱残分）または塗布条件（ロールの圧下力、回転速度など）により調整した。
次いで、上記第二層形成用の塗料組成物をロールコーターにより塗布し、各種温度で加熱乾燥した。皮膜の膜厚は、塗料組成物の固形分（加熱残分）または塗布条件（ロールの圧下力、回転速度など）により調整した。
【０１４５】
得られた表面処理鋼板の皮膜組成と品質性能（耐食性、加工後耐食性、溶接性、電着塗装性）を評価した結果を表９〜表２２に示す。なお、品質性能の評価は以下のようにして行った。
（１）耐食性
各サンプルについて、下記の複合サイクル試験（ＣＣＴ）を施し、３０サイクル経過後の白錆発生面積率および赤錆発生面積率で評価した。
塩水噴霧（ＪＩＳ Ｚ ２３７１に基づく）：４時間
↓
乾燥（６０℃）：２時間
↓
湿潤（５０℃、９５％ＲＨ）：２時間
その評価基準は以下の通りである。
◎ ：白錆発生面積率１０％未満
○ ：白錆発生面積率１０％以上、３０％未満
○−：白錆発生面積率３０％以上で赤錆発生なし
△ ：赤錆発生ありで、赤錆発生面積率１０％未満
× ：赤錆発生面積率１０％以上
【０１４６】
（２）加工後耐食性
各サンプルに対して、下記の条件によるドロービードで変形と摺動を付加し、このサンプルを日本パーカライジング（株）製「ＦＣ−４４６０」を用いて、４５℃、２分間の条件で脱脂した後、前記「（１）耐食性」で行ったＣＣＴを施し、１８サイクル経過後の白錆発生面積率および赤錆発生面積率で評価した。
押付荷重：８００ｋｇｆ
引抜速度：１０００ｍｍ／ｍｉｎ
ビード肩Ｒ：オス側５ｍｍＲ，メス側５ｍｍＲ
押し込み深さ：７ｍｍ
使用油：プレトンＲ−３５２Ｌ
その評価基準は以下の通りである。
◎ ：白錆発生面積率１０％未満
○ ：白錆発生面積率１０％以上、３０％未満
○−：白錆発生面積率３０％以上で、赤錆発生なし
△ ：赤錆発生ありで、赤錆発生面積率１０％未満
× ：赤錆発生面積率１０％以上
【０１４７】
（３）溶接性
各サンプルについて、使用電極：ＣＦ型Ｃｒ−Ｃｕ電極、加圧力：２００ｋｇｆ、通電時間：１０サイクル／５０Ｈｚ、溶接電流：１０ｋＡの条件で連続打点性の溶接試験を行い、連続打点数で評価した。その評価基準は以下の通りである。
◎ ：２０００点以上
○ ：１０００点以上、２０００点未満
△ ：５００点以上、１０００点未満
× ：５００点未満
（４）電着塗装性
各サンプルにカチオン系電着塗料（関西ペイント（株）製「ＧＴ−１０」）を膜厚３０μｍとなるように塗装した後、１３０℃×３０分の焼付を行った。塗装したサンプルを沸水中に２時間浸漬し、直ちに碁盤目（１０×１０個、１ｍｍ間隔）のカットを入れて接着テープによる貼着・剥離を行い、塗膜の剥離面積率を測定した。その評価基準は以下の通りである。
◎ ：剥離なし
○ ：剥離面積率５％未満
△ ：剥離面積率５％以上、２０％未満
× ：剥離面積率２０％以上
【０１４８】
【表１】

【０１４９】
【表２】

【０１５０】
【表３】

【０１５１】
【表４】

【０１５２】
【表５】

【０１５３】
【表６】

【０１５４】
【表７】

【０１５５】
【表８】

【０１５６】
なお、表９〜表２２中に記載の＊１〜＊１０は以下の内容を指す。
＊１：表１に記載のＮｏ．(めっき鋼板)
＊２：表２に記載のＮｏ．(水溶性または水分散性エポキシ樹脂）
＊３：表３に記載のＮｏ．(シランカップリング剤）
＊４：表４に記載のＮｏ．(リン酸またはヘキサフルオロ金属酸)
＊５：表５に記載のＮｏ．(水溶性リン酸塩)
＊６：表６に記載のＮｏ．(防錆添加剤)
＊７：質量部（水溶性または水分散性エポキシ樹脂以外の成分については、水溶性または水分散性エポキシ樹脂の固形分１００質量部に対する質量部）
＊８：表７に記載のＮｏ．(樹脂組成物）
＊９：表８に記載のＮｏ．(固形潤滑剤)
＊１０：質量部（有機樹脂以外の成分については、有機樹脂の固形分１００質量部に対する質量部）
【０１５７】
【表９】

【０１５８】
【表１０】

【０１５９】
【表１１】

【０１６０】
【表１２】

【０１６１】
【表１３】

【０１６２】
【表１４】

【０１６３】
【表１５】

【０１６４】
【表１６】

【０１６５】
【表１７】

【０１６６】
【表１８】

【０１６７】
【表１９】

【０１６８】
【表２０】

【０１６９】
【表２１】

【０１７０】
【表２２】

【０１７１】
[実施例２]
第一層の表面処理皮膜用として、本発明例１〜３では、表２のＮｏ．１の水性エポキシ樹脂分散液に対して、表３のＮｏ．１のシランカップリング剤とリン酸を配合した表面処理組成物を用い、また、比較例では表２のＮｏ．１の水性エポキシ樹脂分散液のみからなる表面処理組成物を用いた。これら表面処理組成物を、表面をアルカリ脱脂処理、水洗乾燥した表１のＮｏ．１のめっき鋼板にロールコーターにより塗布し、１４０℃で加熱乾燥して０．５μｍの膜厚の表面処理皮膜を形成させた。次いで、第二層の上層皮膜用として、本発明例および比較例ともに［実施例１］のＮｏ．３（表１０）と同じ塗料組成物を用い、この塗料組成物を第一層である表面処理皮膜の上にロールコーターにより塗布し、１４０℃で加熱乾燥して１．５μｍの膜厚の上層皮膜を形成させた。
【０１７２】
得られた表面処理鋼板について、[実施例１]と同様の試験条件および評価基準で耐食性と加工後耐食性を評価した。その結果を、第一層および第二層の皮膜構成とともに表２３に示す。
・比較例
表２３の比較例は、第一層の表面処理皮膜が有機樹脂のバリア層のみからなるものであるため耐食性と加工後耐食性は不十分である。
図１に比較例が有する表面処理皮膜に相当する皮膜の皮膜断面電子顕微鏡写真（明視野像）を示す。なお、試料の作成および測定などは先に述べた条件で行った。
【０１７３】
・本発明例１
表２３の本発明例１は、比較例に較べて優れた耐食性と加工後耐食性を有している。
図２に本発明例１が有する表面処理皮膜に相当する皮膜の皮膜断面電子顕微鏡写真（明視野像）を、図３に同じく皮膜断面の組成分析結果（ライン分析：縦軸は原子濃度で表示。なお、Ｃ濃度は大半がオーバースケールとなるため記載を省略。後述する図５、図７についても同様）を、それぞれ示す。なお、試料の作成および測定などは先に述べた条件で行った（後述する図４〜図7についても同様）。これらによれば、下層部分がＰ、ＺｎおよびＯを含み且つＺｎとＰを等モル含んだ化合物層（非晶質化合物層）、上層部分が有機樹脂マトリックス層からなる表面処理皮膜が形成されていることが判る。電子回折パターンによると、上記化合物層は非晶質状である。なお、図３（後述する図５、図７についても同様）において、化合物層中のＺｎとＰが亜鉛めっき皮膜側で等モルからＺｎリッチ側に乖離するのは、電子ビームのプローブ径が有限の大きさを有するため（亜鉛めっき層そのものと化合物層が、化合物層／めっき層界面で同時にプローブ径内に含まれることによる影響）である。
【０１７４】
・本発明例２
表２３の本発明例２は、本発明例１に較べてさらに優れた耐食性と加工後耐食性を有している。
図４に本発明例２が有する表面処理皮膜に相当する皮膜の皮膜断面電子顕微鏡写真（明視野像。なお、図４中の矢印は析出化合物を示し、斜め破線は図５のライン分析位置に対応する）を、図５に同じく皮膜断面の組成分析結果（グラフ中の下向き矢印は析出化合物の位置に対応する）を、それぞれ示す。これらによれば、本発明例１と同様に、表面処理皮膜の下層部分にはＰ、ＺｎおよびＯを含み且つＺｎとＰを等モル含んだ化合物層（非晶質化合物層）が形成されている。さらに、この本発明例２では、表面処理皮膜中にＰ、ＺｎおよびＯを含む化合物が析出している。電子回折パターンによると、上記化合物層および析出化合物は非晶質状である。
【０１７５】
・本発明例３
表２３の本発明例３は、本発明例２に較べてさらに優れた耐食性と加工後耐食性を有している。
図６に本発明例３が有する表面処理皮膜に相当する皮膜の皮膜断面電子顕微鏡写真（明視野像。なお、図６中の矢印は析出化合物を示し、斜め破線は図７のライン分析位置に対応する）を、図７に同じく皮膜断面の組成分析結果（グラフ中の下向き矢印は析出化合物の位置に対応する）を、それぞれ示す。これらによれば、本発明例１，２と同様に、表面処理皮膜の下層部分にはＰ、ＺｎおよびＯを含み且つＺｎとＰを等モル含んだ化合物層（非晶質化合物層）が形成されている。さらに、この本発明例３では、表面処理皮膜中にＺｎ、Ｐ、ＳｉおよびＯを含む化合物が析出している。また、これらの析出化合物は、ＺｎとＰのモル比［Ｚｎ］／［Ｐ］が１．０未満である。電子回折パターンによると、上記化合物層および析出化合物は非晶質状である。
【０１７６】
【表２３】

【０１７７】
なお、表２３中に記載の＊１〜＊７は以下の内容を指す。
＊１：表２に記載のＮｏ．(水分散性エポキシ樹脂）
＊２：表３に記載のＮｏ．(シランカップリング剤）
＊３：表４に記載のＮｏ．(リン酸またはヘキサフルオロ金属酸)
＊４：質量部（水分散性エポキシ樹脂以外の成分については、水分散性エポキシ樹脂の固形分１００質量部に対する質量部）
＊５：表７に記載のＮｏ．(樹脂組成物）
＊６：表６に記載のＮｏ．(防錆添加剤)
＊７：質量部（防錆添加剤については、有機樹脂の固形分１００質量部に対する質量部）
【０１７８】
【発明の効果】
以上述べたように本発明の表面処理鋼板は、皮膜中にクロムを含まないにもかかわらず非常に優れた平板および加工後の耐食性を有し、しかも溶接性、塗装性にも優れている。このため本発明の表面処理鋼板は、自動車用途に特に有用である。
【図面の簡単な説明】
【図１】［実施例２］における比較例の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面組織の電子顕微鏡拡大写真
【図２】［実施例２］における本発明例１の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面組織の電子顕微鏡拡大写真
【図３】［実施例２］における本発明例１の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面の組成分析結果を示すグラフ
【図４】［実施例２］における本発明例２の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面組織の電子顕微鏡拡大写真
【図５】［実施例２］における本発明例２の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面の組成分析結果を示すグラフ
【図６】［実施例２］における本発明例３の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面組織の電子顕微鏡拡大写真
【図７】［実施例２］における本発明例３の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面の組成分析結果を示すグラフ[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a surface-treated steel sheet that is most suitable for use in automobiles, home appliances, and building materials, and particularly relates to an environment-adaptive surface-treated steel sheet that does not contain chromium at all during the production of the surface-treated steel sheet and the surface-treated film, and a method for producing the same. It is.
[0002]
[Prior art]
Conventionally, steel sheets for home appliances, steel sheets for building materials, and steel sheets for automobiles have been used for the purpose of improving corrosion resistance (white rust resistance, red rust resistance) on the surface of galvanized steel sheets or aluminum galvanized steel sheets. Steel plates subjected to chromate treatment with a treatment liquid containing chromic acid or a salt thereof as a main component are widely used. This chromate treatment is an economical treatment method that has excellent corrosion resistance and can be performed relatively easily.
[0003]
Chromate treatment uses hexavalent chromium, a pollution-controlling substance, but this hexavalent chromium is treated in a closed system in the treatment process, completely reduced and recovered, and not released into nature. Since the elution of chromium from the chromate film can be made almost zero by the sealing action of the organic film, the environment and the human body are not substantially contaminated by hexavalent chromium. However, due to recent global environmental problems, there is a growing trend to voluntarily reduce the use of heavy metals including hexavalent chromium. In addition, in order not to pollute the environment when the shredder dust of discarded products is dumped, there has been a movement to minimize or reduce the amount of heavy metals contained in the product.
[0004]
For this reason, in order to prevent the occurrence of white rust in galvanized steel sheets, many treatment techniques that do not rely on chromate treatment, so-called chromium-free techniques, have been proposed. For example, there is a method of forming a thin film by a method such as immersion, coating, or electrolytic treatment using an inorganic compound, an organic compound, an organic polymer material, or a solution combining these.
[0005]
Specifically, the following methods can be listed as conventional techniques.
(1) A method of forming a film by immersing or applying a treatment liquid in a treatment liquid containing a polyhydric phenol carboxylic acid such as tannic acid and a silane coupling agent (for example, Patent Document 1, Patent Document 2, etc.)
(2) A method of forming a film using a treatment liquid in which a polyhydric phenol carboxylic acid such as tannic acid or a phosphoric acid compound is mixed with an organic resin (for example, Patent Documents 3 to 6)
(3) A method of applying a film containing an organic resin and a silane coupling agent (for example, Patent Document 7 to Patent Document 13)
[0006]
[Patent Document 1]
JP 7-216268 A
[Patent Document 2]
Japanese Patent No. 2968959
[Patent Document 3]
JP-A-8-325760
[Patent Document 4]
JP 2000-34578 A
[Patent Document 5]
JP 2000-199076 A
[Patent Document 6]
JP 2000-248380 A
[Patent Document 7]
JP-A-11-106945
[Patent Document 8]
JP 2000-319787 A
[Patent Document 9]
JP 2000-248384 A
[Patent Document 10]
Japanese Patent Laid-Open No. 2000-177871
[Patent Document 11]
JP 2000-199076 A
[Patent Document 12]
JP 2000-281946 A
[Patent Document 13]
Japanese Patent Laid-Open No. 2000-14443
[0007]
[Problems to be solved by the invention]
As the method of (1) above, there is a method of treating with an aqueous solution containing a polyhydric phenol carboxylic acid and a silane coupling agent, and further metal ions, and one of them is a method shown in Patent Document 1 or the like. . However, this treatment method has a drawback that satisfactory adhesion cannot be obtained although good adhesion can be obtained.
As the above method (2), for example, Patent Document 3 discloses a method in which treatment is performed with a treatment liquid in which a polyhydric phenol carboxylic acid, an organic resin, and metal ions are blended. Patent Document 4 discloses a method of immersing in a treatment liquid to which an organic resin and a phosphoric acid compound are added or applying a treatment liquid and then drying. However, although the protective film formed by these treatment liquids contributes to the improvement of the corrosion resistance to some extent, the high degree of corrosion resistance as in the case of the chromate treatment cannot be obtained.
[0008]
As the method (3), for example, Patent Document 8 and Patent Document 9 disclose a method having a film containing an organic resin and a silane coupling agent, and further a thiocarbonyl compound, a phosphate compound, and a vanadium compound. However, the corrosion resistance is not sufficient because the organic resin is polyurethane or acrylic olefin resin. Patent Document 11 has a film made of an acid-modified epoxy resin. Patent Document 10 discloses a resin containing a hydroxyl group / carboxyl group / glycidyl group / phosphate group-containing monomer as a copolymerization component, a silane coupling agent, Although the thing which has the membrane | film | coat which mix | blended the phosphoric acid compound is disclosed, respectively, also about these, corrosion resistance is not enough. Patent Document 7 discloses a film having a film in which an etching agent such as a polyvinylphenol derivative, a silane coupling agent, and phosphoric acid is blended. However, sufficient corrosion resistance cannot be obtained. Patent Document 12 discloses a film having an organic resin blended with an etching agent, and Patent Document 13 discloses a film having a film blended with an organic resin and a silane coupling agent. There is no description and the corrosion resistance is insufficient.
Accordingly, an object of the present invention is to provide a surface-treated steel sheet that solves such problems of the prior art and does not contain chromium in the film and that provides excellent corrosion resistance.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have conducted the following investigation on the principle of corrosion inhibition for inhibiting corrosion of the plated steel sheet.
The corrosion of the zinc-based plated steel sheet on which the surface treatment film is formed proceeds in the following process.
(1) Corrosion factors (oxygen, water, chlorine ions, etc.) permeate into the surface treatment film and diffuse to the plating film / surface treatment film interface.
(2) Zinc dissolves by the following oxidation-reduction reaction at the plating film / surface treatment film interface.
Cathode reaction: 2H₂O + O₂+ 4e⁻ → 4OH⁻
Anode reaction: 2Zn → 2Zn²⁺+ 4e⁻
[0010]
Therefore, to improve the corrosion resistance of the galvanized steel sheet, it is essential to suppress the progress of both reactions (1) and (2).
(1) Advanced barrier layer that acts as a diffusion barrier for corrosion factors (mainly acts to suppress the cathode reaction)
(2) Reaction layer with plating metal that inactivates the surface of the plating film (mainly acts to suppress the anode reaction)
It is most effective to have a film configuration that has a self-repairing action when a defect occurs in the reaction layer.
[0011]
The inventor of the present invention does not form such a film structure by a single coating, but a double-layer film formed by coating the barrier layer forming component and the reaction layer forming component separately as in the prior art. Realization in the layer coating, specifically, the barrier layer (1) (organic resin matrix layer described later) above the coating and the reaction layer (2) amorphous compound (described later) below the coating. It has been found that by forming each layer), more preferably by depositing a substance that causes a self-repairing action in the film, a remarkable corrosion resistance improvement effect can be obtained by these synergistic effects. When such a single-layer coating is defined as a pseudo-two-layer coating, the barrier layer and the reaction layer constituting the pseudo-two-layer coating are between the two-layer coating formed by the conventional double coating. There is no clear interface. On the contrary, it is considered that a high degree of corrosion resistance improvement effect that cannot be obtained by the conventional single layer coating can be exhibited by making the both compositions in a gradient composition.
[0012]
As a result of intensive studies by the present inventors, the quasi-bilayer film as described above is obtained by reacting a water-dispersible liquid of a resin obtained by reacting a specific modified epoxy resin with a hydrazine derivative having active hydrogen, etc. It has been found that a surface treatment composition containing a coupling agent and a specific acid component (phosphoric acid, hexafluorometal acid, etc.) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and dried. It was.
[0013]
A silane coupling agent is known to have an effect of improving the adhesion between an inorganic compound and an organic compound so far, and can improve the adhesion between a plating metal and a water-dispersible resin. In contrast to such known effects of the silane coupling agent, in the present invention, the acid component contained in the surface treatment composition activates the plating film surface by etching, and the silane coupling agent is activated by this activated plating. It is considered that extremely excellent adhesion between the plating metal and the film-forming resin can be obtained by chemically bonding with both the metal and the film-forming resin. That is, by adding a silane coupling agent and a specific acid component to the surface treatment composition, the adhesion between the plating metal and the film-forming resin is markedly greater than when the silane coupling agent is added alone. As a result, it is considered that the progress of corrosion of the plated metal is effectively suppressed and particularly excellent corrosion resistance can be obtained.
[0014]
In the present invention, the mechanism by which the pseudo-bilayer film having the above-described film structure is formed is not necessarily clear, but the reaction between the acid component in the surface treatment composition and the plating film surface may be involved in the film formation. is there. On the other hand, the following actions involving a silane coupling agent are also conceivable. That is, since the silane coupling agent hydrolyzed in an aqueous solution has a silanol group (Si—OH), the hydrogen bonding adsorption action of the silane coupling agent on the surface of the plating metal activated by the acid component is promoted. When the silane coupling agent is concentrated on the metal surface and then dried, a dehydration condensation reaction takes place to form a strong chemical bond, thereby inactivating the reaction layer (2) above the coating layer (that is, the plating film surface layer). (Reaction layer with the plating metal) is formed, and the barrier layer (1) (that is, a high-level barrier layer serving as a diffusion barrier for corrosion factors) is formed by the water-dispersible resin concentrated on the upper part of the film. There is also a possibility by the mechanism. In addition, there is a possibility that the above-described action occurs in a composite manner. In addition, in the film formation process as described above, it is considered that a reaction product (compound) between a dissolved plating metal such as zinc and an acid component is deposited in the film.
[0015]
Although the anti-corrosion mechanism of such a pseudo two-layer coating is not necessarily clear, the individual anti-corrosion mechanism is as follows. (1) As a barrier layer of (1), by adding a hydrazine derivative to a specific modified epoxy resin, A molecular film is formed, which suppresses the permeation of corrosion factors (oxygen, water, chlorine ions, etc.) and effectively suppresses the cathodic reaction that causes corrosion, and also prevents the plating metal ions eluted by the corrosion reaction. The free hydrazine derivative in the film is trapped to form a stable insoluble chelate compound layer, and the reaction layer (2) above effectively inactivates the surface of the plating film and causes an anodic reaction that causes corrosion. In addition, the deposited compounds deposited in the film dissolve in a corrosive environment to produce acid components (phosphate ions, etc.). Captures metal ions such as zinc ions eluted from the plating film (bonds with metal ions to form insoluble compounds), and the silane coupling agent is activated by the acid component. It is possible to form a dense film with high adhesion by binding firmly to the plated metal surface, suppressing dissolution of the plated metal, and bonding with the film-forming resin. Therefore, it is considered that extremely excellent corrosion resistance (white rust resistance) can be obtained.
[0016]
Further, it has been found that further excellent corrosion resistance can be obtained by incorporating a water-soluble phosphate and a non-chromium rust preventive additive into the surface treatment composition. In the same way as above, the poorly soluble film exhibits a barrier against corrosion factors, and the phosphate component captures the eluted plating metal ions, forming an insoluble compound with the plating metal ions. It is possible to do. Further, since the non-chromium rust preventive additive forms a protective film at the starting point of corrosion, further excellent anticorrosive performance can be obtained. In practice, these combined effects provide very good anticorrosion performance.
Furthermore, in the present invention, a particularly high anticorrosive effect can be obtained by forming a high barrier film mainly comprising a specific chelate-forming resin as the second layer film on the surface treatment film described above.
[0017]
The present invention has been made based on such findings, and the features thereof are as follows.
[1] A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and the film thickness formed by drying is 0.01 to Form a surface treatment film of 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper film having a film thickness of 0.5 to 2.0 μm.
[0018]
[2] The film thickness formed by applying a surface treatment composition containing components (a) to (c) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and drying is 0.01 to 1 A surface treatment film of 0.0 μm is formed,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified Obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion in which resin is dispersed in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper film having a film thickness of 0.5 to 2.0 μm.
[0019]
[3] In the surface-treated steel sheet according to [1] or [2], a bisphenol A type epoxy having an epoxy equivalent of 150 to 5000 is an epoxy group-containing resin (B) for obtaining an aqueous epoxy resin dispersion of component (a). A highly corrosion-resistant surface-treated steel sheet which is a resin and has a number average molecular weight of 1500 to 10,000.
[4] The surface-treated steel sheet according to any one of [1] to [3], wherein the aqueous epoxy resin dispersion of component (a) further contains a curing agent having a group that crosslinks with a hydroxyl group. High corrosion resistance surface-treated steel sheet.
[0020]
[5] In the surface-treated steel sheet according to any one of the above [1] to [4], the surface treatment composition for forming a surface treatment film further comprises a water-soluble phosphate, and an aqueous epoxy resin dispersion of component (a) A highly corrosion-resistant surface-treated steel sheet, containing 0.1 to 60 parts by mass of solids with respect to 100 parts by mass of solids.
[6] In the surface-treated steel sheet according to [5] above, the surface treatment composition for forming a surface treatment film is a water-soluble phosphate, a cationic component and P₂O₅Component molar ratio [cation] / [P₂O₅] Is a highly corrosion-resistant surface characterized by containing a water-soluble phosphate having a cation species of at least one selected from Mn, Mg, Al, and Ni Treated steel sheet.
[0021]
[7] In the surface-treated steel sheet according to any one of the above [1] to [6], the surface treatment composition for forming a surface treatment film further comprises a non-chromium rust preventive additive, and an aqueous epoxy resin of component (a) A highly corrosion-resistant surface-treated steel sheet, containing 0.1 to 50 parts by mass of solids with respect to 100 parts by mass of solids in the dispersion.
[8] In the surface-treated steel sheet according to any one of [1] to [7], the upper film further includes a non-chromium rust preventive additive in a ratio of solid content to 100 mass parts of the solid content of the resin composition. A highly corrosion-resistant surface-treated steel sheet characterized by containing 0.1 to 50 parts by mass.
[0022]
[9] In the surface-treated steel sheet according to [7] or [8] above, the surface treatment composition for forming the surface treatment film and / or the upper film is a non-chromium rust preventive additive, and the following (e1) to (e5) A highly corrosion-resistant surface-treated steel sheet, which contains one or more rust preventive additives selected from among the above.
(E1) Silicon oxide
(E2) Calcium and / or calcium compounds
(E3) Insoluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing S atom selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams
[10] In the surface-treated steel sheet according to any one of [1] to [9], the component (b) contains at least one silane coupling agent having an amino group as a reactive functional group as the silane coupling agent. A highly corrosion-resistant surface-treated steel sheet characterized by:
[11] In the surface-treated steel sheet according to any one of the above [1] to [10], the upper film further includes a solid lubricant in a proportion of 1 to 30 in terms of solid content with respect to 100 parts by mass of solid content of the resin composition. A highly corrosion-resistant surface-treated steel sheet containing a mass part.
[0023]
[12] (x) an amorphous compound layer containing P, Zn or / and Al, and O on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and (y) a number average existing above the layer A polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified epoxy resin (A) The film thickness is 0, which is composed of an organic resin matrix layer using a water-dispersible resin obtained by reacting an epoxy group-containing resin (B) other than the hydrazine derivative (C) having active hydrogen as a matrix. Having a surface treatment film of .01 to 1.0 μm,
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper film having a film thickness of 0.5 to 2.0 μm.
[0024]
[13] (x) an amorphous compound layer containing P, Zn or / and Al, and O on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and (y) a number average present in the upper layer A polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified epoxy resin (A) A water-dispersible resin obtained by reacting an epoxy group-containing resin (B) other than hydrazine derivative (C) having active hydrogen with an active hydrogen-containing compound (D) other than hydrazine derivative (C) It has a surface-treated film composed of an organic resin matrix layer as a matrix and having a film thickness of 0.01 to 1.0 μm. And
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper film having a film thickness of 0.5 to 2.0 μm.
[0025]
[14] The surface-treated steel sheet according to [12] or [13], wherein the surface-treated film further contains a silane compound.
[15] The surface-treated steel sheet according to any one of [12] to [14], wherein the surface-treated film contains a precipitation compound containing P, Zn or / and Al, and O, Treated steel sheet.
[16] The surface-treated steel sheet according to any one of [12] to [15], wherein the surface-treated film contains a precipitation compound containing P, Zn or / and Al, Si, and O. Surface treated steel sheet.
[0026]
[17] The surface-treated steel sheet according to any one of [12] to [16], wherein the surface-treated steel sheet has a surface-treated film on the surface of the galvanized steel sheet and an upper film on the surface-treated steel sheet. A highly corrosion-resistant surface-treated steel sheet, wherein the molar ratio [Zn] / [P] of Zn and P in the porous compound layer is 0.9 to 1.4.
[18] The surface-treated steel sheet according to any one of the above [15] to [17], wherein the surface-treated steel sheet has a surface-treated film on the surface of the galvanized steel sheet and an upper film thereon. A highly corrosion-resistant surface-treated steel sheet, wherein the molar ratio [Zn] / [P] of Zn and P in the deposited compound contained in the film is 0.9 to 1.4.
[0027]
[19] The surface-treated steel sheet according to any one of [15] to [17], wherein the surface-treated steel sheet has a surface-treated film on the surface of the zinc-based plated steel sheet and an upper film on the surface-treated steel sheet. A highly corrosion-resistant surface-treated steel sheet, wherein the molar ratio [Zn] / [P] of Zn and P in the deposited compound contained in the film is less than 1.0.
[20] In the surface-treated steel sheet according to any one of [12] to [19], the surface treatment film further includes a non-chromium-based anticorrosive additive in a solid content ratio of 100 parts by mass of the organic resin solid content A highly corrosion-resistant surface-treated steel sheet characterized by containing 0.1 to 50 parts by mass.
[21] In the surface-treated steel sheet according to any one of [12] to [20], the upper film further includes a non-chromium-based rust preventive additive in a solid content ratio of 100 parts by mass of the resin composition. A highly corrosion-resistant surface-treated steel sheet characterized by containing 0.1 to 50 parts by mass.
[0028]
[22] The surface-treated steel sheet according to [20] or [21], wherein the surface-treated film and / or the upper film is selected from the following (e1) to (e5) as a non-chromium-based antirust additive A highly corrosion-resistant surface-treated steel sheet comprising the above rust preventive additive. (E1) Silicon oxide
(E2) Calcium and / or calcium compounds
(E3) Insoluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing S atom selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams
[23] In the surface-treated steel sheet according to any one of [12] to [22], the upper film further includes a solid lubricant in a proportion of 1 to 30 in a solid content ratio with respect to 100 mass parts of the solid content of the resin composition. A highly corrosion-resistant surface-treated steel sheet containing a mass part.
[0029]
[24] A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and dried at a temperature of 30 to 150 ° C. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) A polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet, characterized in that an upper film is formed by applying a coating composition comprising: and drying at a final plate temperature of 30 to 150 ° C. Manufacturing method.
[0030]
[25] A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and dried at a temperature of 30 to 150 ° C. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) A polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified Obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion in which resin is dispersed in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet, characterized in that an upper layer film having a film thickness of 0.5 to 2.0 μm is formed by applying a coating composition comprising: Production method.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention and the reasons for limitation will be described below.
Examples of the zinc-based plated steel sheet used as the base of the surface-treated steel sheet of the present invention include a galvanized steel sheet, a Zn-Ni alloy-plated steel sheet, a Zn-Fe alloy-plated steel sheet (electroplated steel sheet, galvannealed steel sheet), Zn-Cr. Alloy-plated steel sheet, Zn-Mn alloy-plated steel sheet, Zn-Co alloy-plated steel sheet, Zn-Co-Cr alloy-plated steel sheet, Zn-Cr-Ni alloy-plated steel sheet, Zn-Cr-Fe alloy-plated steel sheet, Zn-Al alloy plating Steel plate (for example, Zn-5% Al alloy-plated steel plate, Zn-55% Al alloy-plated steel plate), Zn-Mg alloy-plated steel plate, Zn-Al-Mg-plated steel plate (for example, Zn-6% Al-3% Mg alloy) Plated steel sheet, Zn-11% Al-3% Mg alloy-plated steel sheet), and further, metal oxides, polymers, etc. were dispersed in the plating film of these plated steel sheets Lead-based composite plated steel sheet (for example, Zn-SiO₂(Dispersed plated steel sheet) can be used.
[0032]
In addition, among the above-described plating, a multi-layer plated steel sheet in which two or more layers of the same type or different types are plated can also be used.
Moreover, as an aluminum system plated steel plate used as the base of the surface treatment steel plate of this invention, an aluminum plating steel plate, an Al-Si alloy plating steel plate, etc. can be used.
Moreover, as a plated steel plate, the steel plate surface may be previously plated with lightness such as Ni, and various plating as described above may be performed thereon.
As a plating method, any feasible method among an electrolytic method (electrolysis in an aqueous solution or electrolysis in a non-aqueous solvent), a melting method, and a gas phase method can be adopted.
Furthermore, in order to prevent the blackening of the plating, a trace element of about 1 to 2000 ppm of Ni, Co, Fe is deposited in the plating film, or an alkaline aqueous solution or acid solution containing Ni, Co, Fe on the surface of the plating film. You may make it surface-treat with an aqueous solution and precipitate these elements.
[0033]
Next, the surface treatment film formed as the first layer film and the surface treatment composition for forming this film on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet will be described.
In the surface-treated steel sheet of the present invention, the surface-treated film formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet is applied with a surface treatment composition containing the following components (a) to (c) and dried. It is the surface treatment film formed by this. This surface treatment film does not contain any chromium.
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C) as necessary. Aqueous epoxy resin dispersion in which resin obtained by reaction is dispersed in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
[0034]
First, the aqueous epoxy resin dispersion that is the component (a) will be described.
This aqueous epoxy resin dispersion includes a specific polyalkylene glycol-modified epoxy resin (A), an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), and a hydrazine derivative (C ) And, if necessary, a resin obtained by reacting an active hydrogen-containing compound (D) other than the hydrazine derivative (C), is dispersed in water.
[0035]
The polyalkylene glycol-modified epoxy resin (A) is obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound, and a polyisocyanate compound. .
As the polyalkylene glycol, for example, polyethylene glycol, polypropylene glycol, polybutylene glycol and the like can be used, and among them, polyethylene glycol is particularly preferable. The number average molecular weight of the polyalkylene glycol is suitably in the range of 400 to 20000, preferably 500 to 10,000, from the viewpoint of water dispersibility and storage properties of the resulting resin.
The bisphenol-type epoxy resin is a bisphenol compound having at least one epoxy group in one molecule, and in particular, a bisphenol diester obtained by a condensation reaction between a bisphenol compound and an epihalohydrin (for example, epichlorohydrin). Glycidyl ether is preferable because a film excellent in flexibility and corrosion resistance can be easily obtained.
[0036]
Typical examples of bisphenol compounds that can be used for the preparation of bisphenol-type epoxy resins include bis (4-hydroxyphenyl) -2,2-propane, bis (4-hydroxyphenyl) -1,1-ethane, and bis. (4-hydroxyphenyl) -methane, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl sulfone, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-3-t- Butylphenyl) -2,2-propane and the like. Of the epoxy resins prepared using such bisphenol-based compounds, bisphenol A type epoxy resins are particularly suitable in that a film excellent in flexibility and corrosion resistance can be obtained.
Further, the bisphenol type epoxy resin generally has a number average molecular weight of about 310 to 10,000, particularly preferably about 320 to 2,000, from the viewpoint of production stability during production of the polyalkylene glycol-modified epoxy resin. The epoxy equivalent is preferably in the range of about 155 to 5000, particularly desirably about 160 to 1000.
[0037]
The active hydrogen-containing compound is used for blocking isocyanate groups in the polyalkylene glycol-modified epoxy resin (A). Typical examples thereof include monohydric alcohols such as methanol, ethanol and diethylene glycol monobutyl ether; monovalent carboxylic acids such as acetic acid and propionic acid; monovalent thiols such as ethyl mercaptan. Other blocking agents (active hydrogen-containing compounds) include secondary amines such as diethylamine; one secondary amino group or hydroxyl group such as diethylenetriamine and monoethanolamine and one or more primary groups. A compound in which the primary amino group of an amine compound containing an amino group is modified to aldimine, ketimine, oxazoline or imidazoline by heating reaction with a ketone, aldehyde or carboxylic acid at a temperature of, for example, 100 to 230 ° C .; methyl ethyl ketoxime And oximes such as phenol; phenols such as phenol and nonylphenol; These compounds generally have a number average molecular weight in the range of 30 to 2000, particularly preferably 30 to 200.
[0038]
The polyisocyanate compound is a compound having 2 or more, preferably 2 or 3 isocyanate groups in one molecule, and those generally used for the production of polyurethane resins can be used in the same manner. Such polyisocyanate compounds include aliphatic, alicyclic and aromatic polyisocyanate compounds. Representative examples include aliphatic polyisocyanate compounds such as hexamethylene diisocyanate (HMDI), HMDI biuret compound, HMDI isocyanurate compound; isophorone diisocyanate (IPDI), IPDI biuret compound, IPDI isocyanurate compound, Examples include alicyclic polyisocyanate compounds such as hydrogenated xylylene diisocyanate and hydrogenated 4,4′-diphenylmethane diisocyanate; aromatic polyisocyanate compounds such as tolylene diisocyanate and xylylene diisocyanate.
[0039]
In general, the blending ratio of each component during the production of the polyalkylene glycol-modified epoxy resin (A) is suitably in the following range.
That is, the equivalent ratio of the hydroxyl group of the polyalkylene glycol to the isocyanate group of the polyisocyanate compound is 1 / 1.2 to 1/10, preferably 1 / 1.5 to 1/5, particularly preferably 1 / 1.5 to A value of 1/3 is appropriate. The equivalent ratio of the hydroxyl group of the active hydrogen-containing compound to the isocyanate group of the polyisocyanate compound is 1/2 to 1/100, preferably 1/3 to 1/50, particularly preferably 1/3 to 1/20. Is appropriate. The equivalent ratio of the total amount of hydroxyl groups of the polyalkylene glycol, the bisphenol type epoxy resin and the active hydrogen-containing compound to the isocyanate group of the polyisocyanate compound is 1 / 1.5 or less, preferably 1 / 0.1 to 1/1. .5, particularly preferably 1 / 0.1 to 1 / 1.1.
[0040]
The reaction of the polyalkylene glycol, the bisphenol type epoxy resin, the active hydrogen-containing compound and the polyisocyanate compound can be performed by a known method.
The polyalkylene glycol-modified epoxy resin (A) obtained above, an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and further necessary Accordingly, by reacting with the active hydrogen-containing compound (D) other than the hydrazine derivative (C), an epoxy resin that can be easily dispersed in water and has good adhesion to the material can be obtained. .
[0041]
As the epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), a glycidyl group is introduced by reacting polyphenols such as bisphenol A, bisphenol F, and novolac type phenol with an epihalohydrin such as epichlorohydrin. Or an aromatic epoxy resin obtained by further reacting this glycidyl group-introduced reaction product with a polyphenol to increase the molecular weight; and further, an aliphatic epoxy resin, an alicyclic epoxy resin, etc. One kind can be used alone, or two or more kinds can be mixed and used. These epoxy resins preferably have a number average molecular weight of 1500 or more, particularly when film formation at low temperatures is required.
Examples of the epoxy group-containing resin (B) include resins obtained by reacting various modifiers with epoxy groups or hydroxyl groups in the epoxy group-containing resin. For example, epoxy ester resins obtained by reacting a dry oil fatty acid. An epoxy acrylate resin modified with a polymerizable unsaturated monomer component containing acrylic acid or methacrylic acid; a urethane-modified epoxy resin reacted with an isocyanate compound;
[0042]
Further, as the epoxy group-containing resin (B), an unsaturated monomer having an epoxy group and a polymerizable unsaturated monomer component essentially comprising an acrylic ester or a methacrylic ester are used as a solution polymerization method, emulsion polymerization method or suspension polymerization method. An acrylic copolymer resin copolymerized with an epoxy group-containing monomer synthesized by a method such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl ( Acrylic or methacrylic acid such as (meth) acrylate, n-, iso- or tert-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate C1-C24 Alkyl ester; acrylic acid, methacrylic acid, styrene, vinyl toluene, acrylamide, acrylonitrile, N-methylol (meth) acrylamide, C1-4 alkyl etherified product of N-methylol (meth) acrylamide; N, N-diethylaminoethyl methacrylate, etc. Can be mentioned. Moreover, as an unsaturated monomer which has an epoxy group, if it has an epoxy group and a polymerizable unsaturated group, such as glycidyl methacrylate, glycidyl acrylate, and 3,4 epoxy cyclohexyl-1-methyl (meth) acrylate, It is not limited.
The acrylic copolymer resin may be a resin modified with a polyester resin, an epoxy resin, a phenol resin, or the like.
[0043]
Particularly preferred as the epoxy group-containing resin (B) is a resin represented by the following chemical structural formula, which is a reaction product of bisphenol A and epiparohydrin, and is particularly suitable because of its excellent corrosion resistance.
[Chemical 1]

In said chemical structural formula, q is an integer of 0-50, Preferably it is an integer of 1-40, Most preferably, it is an integer of 2-20.
Such a bisphenol A type epoxy resin can be obtained by a production method widely known in the art.
[0044]
Examples of the active hydrogen-containing compound that reacts with the epoxy group of the epoxy group-containing resin (B) include the following.
・ Hydrazine derivatives with active hydrogen
.Primary or secondary amine compounds having active hydrogen
・ Organic acids such as ammonia and carboxylic acids
・ Hydrogen halides such as hydrogen chloride
・ Alcohols and thiols
· A quaternary chlorinating agent which is a mixture of a hydrazine derivative or a tertiary amine and an acid having no active hydrogen
In preparing the aqueous epoxy resin dispersion, one or more of these can be used, but in order to obtain excellent corrosion resistance, at least a part (preferably all) of the active hydrogen-containing compounds are active. It is necessary to be a hydrazine derivative having hydrogen. That is, among these, a hydrazine derivative (C) having active hydrogen is an essential component, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C) is used as necessary.
[0045]
The following can be mentioned as a typical example of the amine compound which has the said activated hydrogen.
(1) A primary amino group of an amine compound containing one secondary amino group and one or more primary amino groups, such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, and methylaminopropylamine, A compound modified with aldimine, ketimine, oxazoline or imidazoline by heating reaction with aldehyde or carboxylic acid at a temperature of about 100 to 230 ° C., for example;
(2) Secondary monoamines such as diethylamine, diethanolamine, di-n- or -ios-propanolamine, N-methylethanolamine, N-ethylethanolamine;
[0046]
(3) a secondary amine-containing compound obtained by adding a monoalkanolamine such as monoethanolamine and a dialkyl (meth) acrylamide by a Michael addition reaction;
(4) Compounds obtained by modifying primary amine groups of alkanolamines such as monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol, 2-hydroxy-2 '(aminopropoxy) ethyl ether to ketimines;
[0047]
The quaternary chlorinating agent that can be used as a part of the active hydrogen-containing compound can react with an epoxy group because a hydrazine derivative or a tertiary amine that does not have an active hydrogen is not reactive with an epoxy group by itself. Therefore, it is a mixture with an acid. The quaternary chlorinating agent reacts with an epoxy group in the presence of water as necessary to form a quaternary salt with the epoxy group-containing resin. The acid used to obtain the quaternary chlorinating agent may be any of organic acids such as acetic acid and lactic acid, and inorganic acids such as hydrochloric acid. Examples of the hydrazine derivative having no active hydrogen used for obtaining a quaternary chlorinating agent include 3,6-dichloropyridazine, and examples of the tertiary amine include dimethylethanolamine, triethylamine, Examples include trimethylamine, triisopropylamine, and methyldiethanolamine.
[0048]
It is a hydrazine derivative having active hydrogen that exhibits the most useful and excellent corrosion resistance performance among the active hydrogen-containing compounds.
Specific examples of the hydrazine derivative having active hydrogen include the following.
(1) Carbohydrazide, propionic acid hydrazide, salicylic acid hydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, benzophenone hydrazone Hydrazide compounds such as;
(2) Pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole;
[0049]
(3) 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino -3-mercapto-1,2,4-triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (monohydrate), 6- Triazole compounds such as methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine;
[0050]
(4) Tetrazole compounds such as 5-phenyl-1,2,3,4-tetrazole and 5-mercapto-1-phenyl-1,2,3,4-tetrazole;
(5) Thiadiazole compounds such as 5-amino-2-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiadiazole;
(6) Maleic hydrazide, 6-methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4,5-dihydro-3-pyridazone, etc. Pyridazine compounds;
Among these, pyrazole compounds and triazole compounds having a 5-membered or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly suitable.
These hydrazine derivatives can be used individually by 1 type or in mixture of 2 or more types.
[0051]
A polyalkylene glycol-modified epoxy resin (A) as described above, an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and further necessary The active hydrogen-containing compound (D) other than the hydrazine derivative (C) is preferably reacted at a temperature of 10 to 300 ° C., more preferably 50 to 150 ° C. for about 1 to 8 hours. The aqueous epoxy resin dispersion described above can be obtained by dispersing the resin in water.
[0052]
The above reaction may be performed by adding an organic solvent, and the type of the organic solvent to be used is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone, cyclohexanone; ethanol, butanol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether , Propylene glycol, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and other alcohols and ethers containing hydroxyl groups; ethyl acetate, butyl acetate, ethylene glycol monobutyl ether acetate and other esters; toluene, xylene Aromatic hydrocarbons, etc. Indicates possible, it is possible to use one or more of these. Of these, ketone-based or ether-based solvents are particularly preferable from the viewpoints of solubility with an epoxy resin, film formation, and the like.
[0053]
The blending ratio of the polyalkylene glycol-modified epoxy resin (A), the epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), and the hydrazine derivative (C) having active hydrogen is polyalkylene glycol-modified. The equivalent ratio of active hydrogen groups in the hydrazine derivative (C) to the epoxy groups in the epoxy resin (A) and the epoxy group-containing resin (B) is 0.01 to 10, preferably 0.1 to 8, and more preferably 0. 2 to 4 is appropriate from the viewpoints of corrosion resistance and water dispersibility of the resin.
Further, a part of the hydrazine derivative (C) having active hydrogen can be replaced with the active hydrogen-containing compound (D), but the replacement amount is 90 mol% or less, preferably 70 mol% or less, more preferably 10 to 10 mol%. It is suitable from the viewpoint of anticorrosion and adhesion to be in the range of 60 mol%.
[0054]
Moreover, in order to form a dense barrier film, it is desirable to mix a curing agent in the resin composition and heat cure the film. The curing method for forming a film with the resin composition was selected from (1) a curing method using a urethanization reaction between an isocyanate and a hydroxyl group in a base resin, and (2) melamine, urea, and benzoguanamine. Etherification reaction between an alkyl etherified amino resin obtained by reacting one or more methylol compounds obtained by reacting formaldehyde with one or more monovalent alcohols having 1 to 5 carbon atoms and a hydroxyl group in the base resin. However, it is particularly preferable to use a urethanization reaction between an isocyanate and a hydroxyl group in the base resin as a main reaction.
[0055]
The polyisocyanate compound as a curing agent that can be used in the curing method (1) is an aliphatic, alicyclic (including heterocyclic) or aromatic isocyanate compound having at least two isocyanate groups in one molecule. Or a compound obtained by partially reacting these compounds with a polyhydric alcohol. Examples of such polyisocyanate compounds include the following.
[0056]
(1) m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, o- or p-xylylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate
(2) The compound of (1) above or a mixture thereof and a polyhydric alcohol (dihydric alcohols such as ethylene glycol and propylene glycol; trihydric alcohols such as glycerin and trimethylolpropane; tetrahydric alcohols such as pentaerythritol; A reaction product with a hexahydric alcohol such as sorbitol and dipentaerythritol), in which at least two isocyanates remain in one molecule
These polyisocyanate compounds can be used individually by 1 type or in mixture of 2 or more types.
[0057]
Moreover, as a protective agent (blocking agent) of a polyisocyanate compound, for example,
(1) Aliphatic monoalcohols such as methanol, ethanol, propanol, butanol, octyl alcohol;
(2) Ethylene glycol and / or diethylene glycol monoethers, for example, monoethers such as methyl, ethyl, propyl (n-, iso), butyl (n-, iso, sec);
(3) Aromatic alcohols such as phenol and cresol;
(4) Oxime such as acetoxime and methyl ethyl ketone oxime;
A polyisocyanate compound that is stably protected at least at room temperature can be obtained by reacting one or more of these with the polyisocyanate compound.
[0058]
Such a polyisocyanate compound (a2) has a curing agent of (a) / (a2) = 95/5 to 55/45 (nonvolatile) with respect to the aqueous epoxy resin dispersion (a) (the component (a)). (Mass ratio of minute), preferably (a) / (a2) = 90/10 to 65/35. The polyisocyanate compound has water absorption, and if it is blended in excess of (a) / (a2) = 55/45, the adhesion of the surface treatment film is deteriorated. Furthermore, the unreacted polyisocyanate compound moves into the upper layer film, which causes inhibition of curing of the upper layer film and poor adhesion. From such a viewpoint, the blending amount of the polyisocyanate compound (a2) is preferably (a) / (a2) = 55/45 or less.
[0059]
The water-dispersible resin is sufficiently crosslinked by the addition of the crosslinking agent (curing agent) as described above, but it is desirable to use a known curing accelerating catalyst in order to further increase the low-temperature crosslinking property. Examples of the curing accelerating catalyst include N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, and bismuth nitrate.
In addition, for the purpose of slightly improving physical properties such as adhesion, a known resin such as acrylic, alkyd, or polyester can be mixed and used together with the epoxy group-containing resin (B).
[0060]
The reaction product of polyalkylene glycol-modified epoxy resin (A), epoxy group-containing resin (B) and hydrazine derivative (C) having active hydrogen (and active hydrogen-containing compound (D) if necessary) is dispersed in water. For example, the following method can be employed.
(1) A tertiary amine as a neutralizing agent by reacting an epoxy group of an epoxy group-containing resin (ie, resin (A) or (B)) with a dibasic acid or secondary amine as an active hydrogen-containing compound. , Neutralization with acetic acid or phosphoric acid, water dispersion method
(2) A method of dispersing in water by using a modified epoxy resin obtained by reacting an epoxy resin with a polyalkylene oxide having a terminal hydroxyl group such as polyethylene glycol or polypropylene glycol with an isocyanate as a dispersant.
(3) Method using both (1) and (2) above
[0061]
In the surface treatment composition, in addition to the specific water-dispersible resin described above, other water-dispersible resins and / or water-soluble resins include, for example, acrylic resins, urethane resins, polyester resins, epoxy resins, You may mix | blend 1 type (s) or 2 or more types, such as ethylene-type resin, alkyd-type resin, a phenol resin, and an olefin resin, by about 15 mass% by the ratio in the total resin solid content.
[0062]
Next, the silane coupling agent which is the said component (b) is demonstrated.
Examples of the silane coupling agent include vinyl methoxy silane, vinyl ethoxy silane, vinyl trichloro silane, vinyl trimethoxy silane, vinyl triethoxy silane, β- (3,4 epoxy cyclohexyl) ethyl trimethoxy silane, and γ-glycid. Xylpropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ -Aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-me Tacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, p-styryltrimethoxysilane, γ -Acryloxypropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, γ-isocyanatopropyl Triethoxysilane, γ-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N- (vinylbenzylamine) -β-aminoethyl-γ-aminopropyltri Etc. can be mentioned Tokishishiran, these one may be used alone or in combination of two or more.
[0063]
In the present invention, the reason described above is considered to improve the white rust resistance by including a silane coupling agent together with a specific acid component in the surface treatment composition.
Among the silane coupling agents, a silane coupling agent having an amino group as a reactive functional group is particularly preferable from the viewpoint of having a functional group highly reactive with the water-dispersible resin of the component (a). preferable. Examples of such silane coupling agents include N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ. -Aminopropyltrimexysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, etc., specifically, “KBM-903” and “KBE-903” manufactured by Shin-Etsu Chemical Co., Ltd. , “KBM-603”, “KBE-602”, “KBE-603” (all are trade names), and the like.
[0064]
The compounding quantity of a silane coupling agent is 1-300 mass parts with respect to 100 mass parts of solid content of the aqueous | water-based epoxy resin dispersion which is the said component (a), Preferably it is 5-100 mass parts, More preferably, it is 15-50. The mass part is appropriate. If the amount of the silane coupling agent is less than 1 part by mass, the corrosion resistance is inferior. On the other hand, if it exceeds 300 parts by mass, a sufficient film cannot be formed, so that the effect of improving the adhesion and barrier properties with the water-dispersible resin can be exhibited. Therefore, the corrosion resistance is reduced.
[0065]
Next, phosphoric acid and / or hexafluorometal acid, which is the component (c), acts on an inactive plating metal surface to activate the plating metal surface. The phosphoric acid and hexafluorometal acid may be used alone or in combination.
The type of hexafluorometal acid is not particularly limited, but in particular hexafluorometal containing one or more elements selected from Ti, Si, Zr such as fluorinated titanate, fluorinated zirconate, and fluoric acid. Acids are preferred, and one or more of these can be used.
[0066]
The total amount of phosphoric acid and / or hexafluorometal acid is 0.1 to 80 parts by mass, preferably 1 to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion as component (a). 60 mass parts, more preferably 5-50 mass parts is suitable. If the blending amount of phosphoric acid and / or hexafluorometal acid is less than 0.1 parts by mass, the corrosion resistance is inferior. On the other hand, if it exceeds 80 parts by mass, the soluble component of the film increases, so that the corrosion resistance decreases.
[0067]
A water-soluble phosphate can be added to the surface treatment composition as necessary for the purpose of improving the corrosion resistance. As this water-soluble phosphate, for example, one or more metal salts such as orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, and metaphosphoric acid can be used. Moreover, you may add 1 or more types of the salt (for example, phytic acid, phytate, phosphonic acid, phosphonate, and these metal salts) of organic phosphoric acid. Of these, the primary phosphate is preferable from the viewpoint of the stability of the surface treatment composition.
There is no particular limitation on the form of phosphate present in the film, and it may be crystalline or non-crystalline. There are no particular restrictions on the ionicity and solubility of the phosphate in the film. The reason why the corrosion resistance is improved by adding the water-soluble phosphate is considered that the water-soluble phosphate forms a dense hardly soluble compound at the time of film formation.
[0068]
As described above, the silane coupling agent chemically bonds with both the activated plating metal and the film-forming resin, thereby providing excellent adhesion and corrosion resistance between the plating metal and the film-forming resin. There are unavoidably inactive portions on the metal surface, and such an inactive site hardly causes the above-mentioned chemical bond and cannot sufficiently exhibit the rust prevention effect. The water-soluble phosphate forms a dense hardly soluble compound at the time of film formation on such a plated film portion. That is, as the plating film is dissolved by the phosphate ions of the water-soluble phosphate, the pH increases at the plating film / surface treatment composition interface, resulting in the formation of a precipitate film of the water-soluble phosphate, which is corrosion resistant. It contributes to the improvement.
[0069]
Further, from the viewpoint of obtaining particularly excellent corrosion resistance, Al, Mn, Ni, and Mg are particularly desirable as the cationic species of the water-soluble phosphate, and the water-soluble salt contains one or more elements selected from these. It is preferable to use a phosphate. Examples of such water-soluble phosphates include primary aluminum phosphate, primary manganese phosphate, primary nickel phosphate, primary magnesium phosphate, and among these, primary aluminum phosphate is particularly preferable. Is most preferred. The cationic component and P₂O₅Component molar ratio [cation] / [P₂O₅] Is preferably 0.4 to 1.0. Molar ratio [cation] / [P₂O₅] Is less than 0.4, it is not preferable because soluble phosphoric acid impairs the poor solubility of the film and lowers the corrosion resistance. On the other hand, if it exceeds 1.0, the stability of the processing solution is significantly lost, which is not preferable.
[0070]
The blending amount of the water-soluble phosphate is 0.1 to 60 parts by mass, preferably 0.00 with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion as the component (a). 5 to 40 parts by mass, more preferably 1 to 30 parts by mass is appropriate. If the blending amount of the water-soluble phosphate is less than 0.1 parts by mass, the effect of improving the corrosion resistance is not sufficient. On the other hand, if it exceeds 60 parts by mass, the soluble component of the film increases, so the corrosion resistance decreases, which is not preferable. .
[0071]
A non-chromium rust preventive additive can be blended with the surface treatment composition as needed for the purpose of improving corrosion resistance. Particularly excellent anticorrosion performance (self-repairing property) can be obtained by blending such a non-chromium rust preventive additive into the surface treatment composition.
In particular, it is preferable to use one or more selected from the following (e1) to (e5) as the non-chromium rust preventive additive.
(E1) Silicon oxide
(E2) Calcium or calcium compound
(E3) Insoluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing S atom selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams
The details of these (e1) to (e5) non-chromium rust preventive additives and the anticorrosion mechanism are as follows.
[0072]
First, as the component (e1), colloidal silica or dry silica, which is fine particle silica, can be used. From the viewpoint of corrosion resistance, calcium ion-exchanged silica in which calcium is bound to the surface is used. Is desirable.
As colloidal silica, for example, SNOWTEX O, 20, 30, 40, C, S (all trade names) manufactured by Nissan Chemical Co., Ltd. can be used, and as fumed silica, Nippon Aerosil ( AEROSIL R971, R812, R811, R974, R202, R805, 130, 200, 300, 300CF (all trade names) manufactured by Co., Ltd. can be used. As calcium ion exchange silica, W.R.Grace & Co. SHIELDEX C303, SHIELDEX AC3, SHIELDEX AC5 (all are trade names) manufactured by SHIELDEX, SHIELDEX SY710 (all are trade names) manufactured by Fuji Silysia Chemical Co., Ltd., and the like can be used. These silicas contribute to the production of dense and stable zinc corrosion products in a corrosive environment, and the corrosion products are formed densely on the plating surface, thereby suppressing the promotion of corrosion.
[0073]
In addition, the above components (e2) and (e3) exhibit particularly excellent anticorrosion performance (self-repairing property) due to precipitation.
The calcium compound as the component (e2) may be any of calcium oxide, calcium hydroxide, and calcium salt, and one or more of these can be used. In addition, there are no particular restrictions on the type of calcium salt. In addition to simple salts containing only calcium as a cation such as calcium silicate, calcium carbonate, and calcium phosphate, calcium and calcium such as calcium phosphate / zinc, calcium phosphate / magnesium, etc. Double salts containing other cations may be used. This (e2) component is preferentially dissolved in base metal over zinc and aluminum, which are plated metals, in a corrosive environment.⁻As a dense and sparingly soluble product, it blocks the defective part and suppresses the corrosion reaction. Moreover, when it mix | blends with the above silicas, a calcium ion adsorb | sucks to the surface and neutralizes a surface charge electrically and aggregates. As a result, a dense and sparingly soluble protective film is formed to block the corrosion and suppress the corrosion reaction.
[0074]
Further, as the hardly soluble phosphate compound (e3), a hardly soluble phosphate can be used. This sparingly soluble phosphate includes all types of salts such as simple salts and double salts. Moreover, there is no limitation in the metal cation which comprises it, and any metal cation, such as poorly soluble zinc phosphate, magnesium phosphate, calcium phosphate, aluminum phosphate, may be sufficient. Further, there is no limitation on the skeleton or the degree of condensation of phosphate ions, and any of normal salt, dihydrogen salt, monohydrogen salt or phosphite may be used. In addition, orthophosphate may be polyphosphate other than orthophosphate. Includes all condensed phosphates such as salts. This hardly soluble phosphorus compound is a metal plating zinc or aluminum eluted by corrosion, and forms a dense and hardly soluble protective film by a complexing reaction with phosphate ions dissociated by hydrolysis, thereby blocking the corrosion starting point. Inhibits corrosion reactions.
[0075]
As the molybdate compound (e4), for example, molybdate can be used. The molybdate is not limited in its skeleton and degree of condensation, and examples thereof include orthomolybdate, paramolybdate, and metamolybdate. Moreover, all salts, such as a single salt and a double salt, are included, and phosphoric acid molybdate etc. are mentioned as a double salt. Molybdate compounds exhibit self-repairing properties due to the passivating effect. That is, by forming a dense oxide on the plating film surface together with dissolved oxygen in a corrosive environment, the corrosion starting point is blocked and the corrosion reaction is suppressed.
[0076]
Examples of the organic compound (e5) include the following. That is, as triazoles, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino-3-mercapto-1,2 1,4-triazole, 1H-benzotriazole, etc., and as thiols, 1,3,5-triazine-2,4,6-trithiol, 2-mercaptobenzimidazole, etc., and as thiadiazoles, 5- Amino-2-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole and the like, and as thiazoles, 2-N, N-diethylthiobenzothiazole, 2-mercapto Examples include benzothiazoles, and examples of thiurams include tetraethylthiuram disulfide. It is. These organic compounds exhibit self-repairing properties due to the adsorption effect. That is, zinc and aluminum eluted by corrosion are adsorbed on polar groups containing sulfur contained in these organic compounds to form an inert film, thereby blocking the corrosion starting point and suppressing the corrosion reaction.
[0077]
The compounding amount of the non-chromium rust preventive additive is 0.1 to 50 parts by mass, preferably 0 with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion as the component (a). It is appropriate that the content is 5 to 30 parts by mass. If the blending amount of the non-chromium rust preventive additive is less than 0.1 parts by mass, the effect of improving the corrosion resistance after alkali degreasing cannot be sufficiently obtained. On the other hand, if it exceeds 50 parts by mass, the paintability and workability deteriorate. In addition, the corrosion resistance is reduced, which is not preferable.
Two or more rust preventive additives (e1) to (e5) may be added in combination. In this case, since the inherent anticorrosive action is combined, higher corrosion resistance can be obtained. In particular, calcium ion-exchanged silica is used as the component (e1), and one or more of the components (e3), (e4), and (e5), particularly preferably the components (e3) to (e5). When all are added in combination, particularly excellent corrosion resistance is obtained.
[0078]
Further, in the surface treatment film (and surface treatment composition), other oxide fine particles (for example, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide, etc.), phosphomolybdate as corrosion inhibitors. One or more kinds of organic inhibitors (for example, hydrazine and its derivatives, thiol compounds, thiocarbamates, etc.) can be added.
[0079]
Further, if necessary, in the surface treatment film (and surface treatment composition), as an additive, an organic coloring pigment (for example, condensed polycyclic organic pigment, phthalocyanine organic pigment, etc.), a coloring dye (for example, water-soluble) Azo metal dyes), inorganic pigments (eg, titanium oxide), conductive pigments (eg, metal powders such as zinc, aluminum, nickel, iron phosphide, antimony-doped tin oxide, etc.), coupling agents (eg, 1 type, or 2 or more types, such as a titanium coupling agent etc.) and a melamine cyanuric acid adduct.
The surface treatment film formed by the surface treatment composition containing the above components has a dry film thickness of 0.01 to 1.0 μm, preferably 0.1 to 0.8 μm. When the dry film thickness is less than 0.01 μm, the corrosion resistance is insufficient. On the other hand, when the dry film thickness exceeds 1.0 μm, the conductivity and workability are lowered.
[0080]
Next, a specific film structure of the surface treatment film described above will be described.
In the present invention, the film structure of the surface treatment film formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet includes an amorphous compound layer containing P, Zn or / and Al, and O, and an hydrazine layer thereon A specific epoxy group-containing resin modified with a derivative, that is, a polyalkylene glycol-modified epoxy resin obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound (A), an epoxy group-containing resin (B) other than this polyalkylene glycol-modified epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and, if necessary, other than this hydrazine derivative (C) Obtained by reacting with active hydrogen-containing compound (D) It consists of an organic resin matrix layer containing a water-dispersible resin as a matrix, and preferably contains P, Zn or / and Al, and O in the film (amorphous compound layer or / and organic resin matrix layer). Precipitated compounds, more preferably those containing P, Zn or / and precipitated compounds containing Al, Si and O. This surface treatment film does not contain any chromium.
[0081]
In order to give excellent corrosion resistance (white rust resistance) to the base-plated steel sheet such as galvanized steel sheet by the chromium-free film, as mentioned above,
(1) An advanced barrier layer serving as a diffusion barrier for corrosion factors is formed by an organic resin to suppress the cathode reaction.
(2) A dense inactive layer (reaction layer) is formed on the surface of the plating film by the reaction between the surface treatment composition and the surface of the plating film, and the anode reaction is suppressed by the inactivating action of the surface of the plating film by this inactive layer. To do.
Is more effective, and more preferably
(3) It has a self-repairing substance that reacts with the defective part (or damaged part) of the above-mentioned inactive layer and repairs it, and traps and makes the metal ions such as zinc ions to be eluted from the part difficult to dissolve (ie , Has self-repairability).
It is effective.
[0082]
According to the surface-treated film of the surface-treated steel sheet according to the present invention, the upper organic resin matrix layer provides a high level of barrier properties (the effect of (1) above), and the lower amorphous compound layer. The surface of the plating film is inactivated by the above-described (2) action, and the self-repairing property (3) is preferably imparted by the precipitated compound contained in the film. A high degree of corrosion resistance is imparted to the surface-treated steel sheet due to the combined action.
The amorphous compound layer is a concentrated layer or film of an amorphous compound formed by the reaction of the surface treatment composition and the plating film surface layer, and is derived from Zn, Al, which is a plating film component, or Zn / And a compound containing Al. When the plated steel sheet is a zinc-based plated steel sheet, the compositional feature of the amorphous compound is that it contains equimolar amounts of Zn and P. More specifically, the molar ratio of Zn and P [Zn] / [P ] Is 0.9 to 1.4. This compound is a diphosphate-based compound (for example, ZnHPO₄・ 2H₂O).
[0083]
The excellent white rust resistance is obtained by forming such an amorphous compound layer, as already described, by inactivating the surface layer of the plating layer by this amorphous compound layer, This is considered to be because even when the corrosion factor penetrates the upper barrier layer (organic resin matrix layer) and reaches the surface of the plating film, the anode reaction related to the generation of white rust is suppressed.
The thickness of the amorphous compound layer is preferably 10 nm or more from the viewpoint of corrosion resistance.
In order to positively form the amorphous compound layer, it is preferable to perform the heat treatment after applying the surface treatment composition by an induction heating method (induction heating furnace). This is because in the heating by the induction heating method, since the heating is performed from the steel plate side, the reaction between the plating film and the surface treatment composition is promoted, which is an advantageous condition for the formation of the amorphous compound layer.
[0084]
The surface treatment film usually contains a silane compound derived from the silane coupling agent contained in the surface treatment composition. In addition, this silane compound also includes the case where it contains by the composition as a silane coupling agent.
Moreover, in order to provide a high degree of white rust resistance by the surface treatment film, it is preferable that the surface treatment film contains a specific precipitation compound. This precipitation compound is an amorphous precipitation compound containing P, Zn or / and Al, and O. Furthermore, when this precipitation compound contains Si, the effect of improving white rust resistance is further enhanced. Zn and Al contained in the deposited compound are derived from Zn and Al as plating film components, and Si is derived from a silane coupling agent contained in the surface treatment composition.
[0085]
The deposited compound is considered to be a reaction product (compound) of the plating metal dissolved from the plating film and mainly the acid component in the surface treatment composition, and an appropriate amount of acid component (phosphoric acid, etc.) in the surface treatment composition. ) Can be generated (deposited) in the film. Moreover, the precipitation compound containing Si among the above precipitates is one in which the silane coupling agent component in the surface treatment composition is incorporated into the compound, and such a precipitation compound is also contained in the surface treatment composition. By optimizing the addition amount of the silane coupling agent (making the addition amount relatively large), it can be generated (deposited) in the film.
[0086]
The reason why white rust resistance is improved by the inclusion of the above-mentioned precipitation compound in the surface treatment film is not necessarily clear, but acid components such as phosphate ions eluted from the precipitation compound are eluted from the plating film during the corrosion process. It is presumed that this is because an insoluble compound is produced by binding with a metal ion such as zinc ion, and a stable precipitation protective film is formed to suppress corrosion (exhibit self-repair properties).
In addition, the reason why a more excellent white rust resistance can be obtained by including Si in the precipitated compound is not necessarily clear, but the inclusion of Si increases the solubility of the precipitated compound in a corrosive environment. Factors such as the fact that the reaction product with metal ions such as zinc ions eluted from the plating film during the corrosion process become more stable due to the incorporation of Si in the amorphous compound layer can be considered.
When the plated steel sheet is a zinc-based plated steel sheet, the precipitation compound contained in the surface treatment film usually contains equimolar amounts of Zn and P. More specifically, the molar ratio [Zn] / [P] of Zn and P is 0.9 to 1.4, and this compound is a diphosphate compound (for example, ZnHPO).₄・ 2H₂O).
[0087]
On the other hand, when a deposited compound having a Zn / P molar ratio [Zn] / [P] of less than 1.0 was deposited in the surface treatment film, a deposited compound containing equimolar Zn and P was deposited. Compared to the case, the white rust resistance is further improved. The precipitated compound having a molar ratio [Zn] / [P] of less than 1.0 is a water-soluble primary phosphate (for example, Zn (H₂PO₄)₂・ H₂O) Presumed to be the main compound. The reason why particularly excellent white rust resistance can be obtained by precipitating such a compound is not necessarily clear, but this precipitating compound is a metal such as zinc ion that tends to elute from the defect portion of the amorphous compound layer. It is presumed that this is because it reacts with ions to form a sparingly soluble diphosphate (for example, dibasic zinc phosphate) to perform a high function as a self-repairing substance.
[0088]
As described above, the film thickness of the surface treatment film described above is 0.01 to 2.0 μm, preferably 0.1 to 1.5 μm. Further, as described above, a non-chromium rust preventive additive, a solid lubricant and the like can be contained in the surface treatment film.
Further, the surface treatment composition for forming the surface treatment film needs to be an aqueous solvent type in order to generate a compound layer (amorphous compound layer) or a precipitated compound as described above, and therefore organic A water dispersible resin is used as the resin.
[0089]
Next, the detail of the measuring method of the film | membrane composition of the surface treatment film | membrane mentioned above is demonstrated. The quantitative value of the local composition of the cross-section of the film obtained by the transmission electron microscope and the energy dispersive X-ray analyzer, which are widely used at present, is the cross-section sample preparation method, data measurement conditions, data processing method, quantitative correction calculation The reality is that it changes depending on the law. This is because (1) it is virtually impossible to prepare a standard sample for elemental analysis suitable for an unknown sample that can be observed with a transmission electron microscope, so quantitative calculation based on theoretical calculation without using a standard sample is possible. The reason is that there are various calculation models for it, and (2) the quantitative calculation method for the relative concentration of heavy elements over Na to light elements under Na has not been established worldwide. Is due to. In addition to such a situation, how to handle characteristic X-rays from other than the measurement target portion due to the shape of the cross-sectional sample, the support for the cross-sectional sample, and the like greatly affects the quantitative result.
[0090]
Therefore, in the present invention, the following method was used for the measurement of the film composition. First, a microsampling mechanism attached to a focused ion beam processing apparatus (Focused Ion Beam: FIB) FB2000A manufactured by Hitachi, Ltd. was used to prepare a cross-sectional sample for a transmission electron microscope. Prior to FIB processing, a protective film of C was flash-deposited around 200 nm on the surface of the sample piece of the surface-treated steel sheet for preparing the cross-section sample, in order to protect it from damage caused by ion beam irradiation. Further, a protective film of Au was sputter coated with about 100 nm. The surface of the cross-section sample cut-out portion of the test material introduced into the FIB processing apparatus is further coated with a C protective film around 500 nm using the chemical vapor deposition (CVD) mechanism of the FIB processing apparatus, and then the cross-section sample is cut out. Processing was performed. The cross-sectional sample taken out using the microsampling mechanism was fixed to a straight portion of a Mo meniscus special mesh using a CVD mechanism, and finished to a film thickness suitable for transmission electron microscope observation.
For the compositional analysis of the cross-sectional sample thus prepared, energy from EDAX equipped with a Philips transmission electron microscope CM20FEG equipped with a field emission electron gun and a Super-UTW type detector attached thereto. A distributed X-ray analyzer, Phoenix, was used. Note that the acceleration voltage during microscopic image observation and elemental analysis was 200 kV.
[0091]
The composition of the amorphous compound layer and the precipitated compound was determined by performing background removal, peak separation, and quantitative correction calculation from the spectrum data collected from these positions. At that time, if the background processing is performed automatically, the net intensity (net intensity) in the light element region may not be calculated properly. Therefore, manually specify the energy position where the peak does not appear and connect it manually. Treated (removed) by ground method. In the peak separation, characteristic X-rays such as Mo and Au caused by the Mo mesh used as a support for the cross-sectional sample and Au protective layer, and Ga caused by FIB processing were also considered. All quantitative calculations were performed using K-series characteristic X-rays of each element contained in the chemical conversion coating. The correction calculation is performed by thin film approximation, and a correction factor (so-called K_ABThe factor was the Zaluzec model.
The molar ratio of Zn and P of the amorphous compound layer of the surface treatment film and the precipitated compound can be obtained as the ratio of the atomic concentration of Zn and P thus determined.
[0092]
Next, the upper layer film (organic film) formed as the second layer film on the surface treatment film will be described.
This upper layer film is a reaction product of the main component of the resin composition of the film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. It is a film having a film thickness of 0.5 to 2.0 μm. This upper layer film also contains no chromium.
[0093]
As the kind of the film-forming organic resin (E), a part or all of the compounds react with the active hydrogen-containing compound (F) composed of the hydrazine derivative (G) having active hydrogen, so that the film-forming organic resin contains active hydrogen. There is no particular limitation as long as the compound (F) can be bonded by a reaction such as addition or condensation and can form a film appropriately. Examples of the film-forming organic resin (E) include epoxy resins, modified epoxy resins, polyurethane resins, polyester resins, alkyd resins, acrylic copolymer resins, polybutadiene resins, phenol resins, and adducts of these resins or A condensate etc. can be mentioned, One of these can be used individually or in mixture of 2 or more types.
[0094]
In addition, as the film-forming organic resin (E), an epoxy group-containing resin (H) containing an epoxy group in the resin is particularly preferable from the viewpoints of reactivity, easiness of reaction, corrosion resistance, and the like. As this epoxy group-containing resin (H), a part or all of the compounds react with the active hydrogen-containing compound (F) made of the hydrazine derivative (G) having active hydrogen to form an active hydrogen-containing compound in the film-forming organic resin. There is no particular limitation as long as (F) is a resin that can be bonded by a reaction such as addition or condensation and can form a film appropriately. For example, an acrylic resin copolymerized with an epoxy resin, a modified epoxy resin, or an epoxy group-containing monomer. Examples thereof include copolymer resins, polybutadiene resins having an epoxy group, polyurethane resins having an epoxy group, and adducts or condensates of these resins. One of these epoxy group-containing resins may be used alone or in combination of two or more. It can be used by mixing.
Of these epoxy group-containing resins (H), epoxy resins and modified epoxy resins are particularly suitable from the viewpoints of adhesion to the plating surface and corrosion resistance. Among them, thermosetting epoxy resins and modified epoxy resins that have excellent barrier properties against corrosion factors such as oxygen are the most suitable, and in particular, the coating amount to obtain high conductivity and spot weldability. It is particularly advantageous when the level is low.
[0095]
As the epoxy resin, polyphenols such as bisphenol A, bisphenol F, and novolac type phenol are reacted with epihalohydrin such as epichlorohydrin to introduce glycidyl groups, or polyphenols are further added to the glycidyl group introduction reaction product. An aromatic epoxy resin obtained by reacting with an aromatic epoxy resin, an aliphatic epoxy resin, an alicyclic epoxy resin, and the like. These may be used alone or in admixture of two or more. Can do. These epoxy resins preferably have a number average molecular weight of 1500 or more, particularly when film formation at low temperatures is required.
[0096]
Examples of the modified epoxy resin include resins obtained by reacting various modifiers with epoxy groups or hydroxyl groups in the epoxy resin, such as epoxy ester resins reacted with drying oil fatty acids, acrylic acid, methacrylic acid, etc. An epoxy acrylate resin modified with a polymerizable unsaturated monomer component containing styrene, a urethane-modified epoxy resin reacted with an isocyanate compound, and the like can be exemplified.
[0097]
As the acrylic copolymer resin copolymerized with the epoxy group-containing monomer, an unsaturated monomer having an epoxy group and a polymerizable unsaturated monomer component essentially comprising an acrylic ester or a methacrylic ester, a solution polymerization method, Examples thereof include resins synthesized by an emulsion polymerization method or a suspension polymerization method.
Examples of the polymerizable unsaturated monomer component include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-, iso- or tert-butyl (meth) acrylate, hexyl (meth) acrylate, C1-24 alkyl ester of acrylic acid or methacrylic acid such as 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate; acrylic acid, methacrylic acid, styrene, vinyltoluene, acrylamide, acrylonitrile, N- Examples thereof include methylol (meth) acrylamide, C1-4 alkyl etherified product of N-methylol (meth) acrylamide; N, N-diethylaminoethyl methacrylate and the like.
[0098]
The unsaturated monomer having an epoxy group is not particularly limited as long as it has an epoxy group and a polymerizable unsaturated group, such as glycidyl methacrylate, glycidyl acrylate, and 3,4-epoxycyclohexylmethyl (meth) acrylate. .
The acrylic copolymer resin copolymerized with the epoxy group-containing monomer may be a resin modified with a polyester resin, an epoxy resin, a phenol resin, or the like.
[0099]
Particularly preferable as the epoxy resin is a resin having a chemical structure represented by the following formula, which is a reaction product of bisphenol A and epihalohydrin, and this epoxy resin is particularly preferable because of its excellent corrosion resistance.
[Chemical formula 2]

A method for producing such a bisphenol A type epoxy resin is widely known in the art. Moreover, in the said chemical structural formula, q is 0-50, Preferably it is 1-40, Most preferably, it is 2-20.
The film-forming organic resin (E) may be any of an organic solvent dissolution type, an organic solvent dispersion type, a water dissolution type, and a water dispersion type.
[0100]
The present invention aims to provide a hydrazine derivative in the molecule of the film-forming organic resin (E). Therefore, at least part (preferably all) of the active hydrogen-containing compound (F) is hydrazine having active hydrogen. It must be a derivative (G).
When the film-forming organic resin (E) is an epoxy group-containing resin, examples of the active hydrogen-containing compound (F) that reacts with the epoxy group include those shown below. In this case as well, at least a part (preferably all) of the active hydrogen-containing compound (F) needs to be a hydrazine derivative having active hydrogen.
・ Hydrazine derivatives with active hydrogen
.Primary or secondary amine compounds having active hydrogen
・ Organic acids such as ammonia and carboxylic acids
・ Hydrogen halides such as hydrogen chloride
・ Alcohols and thiols
· A quaternary chlorinating agent which is a mixture of a hydrazine derivative or a tertiary amine and an acid having no active hydrogen
[0101]
Examples of the hydrazine derivative (G) having active hydrogen include the following.
(1) Carbohydrazide, propionic acid hydrazide, salicylic acid hydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, benzophenone hydrazone Hydrazide compounds such as;
(2) Pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole;
[0102]
(3) 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino -3-mercapto-1,2,4-triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (monohydrate), 6- Triazole compounds such as methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine;
[0103]
(4) Tetrazole compounds such as 5-phenyl-1,2,3,4-tetrazole and 5-mercapto-1-phenyl-1,2,3,4-tetrazole;
(5) Thiadiazole compounds such as 5-amino-2-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiadiazole;
(6) Maleic hydrazide, 6-methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4,5-dihydro-3-pyridazone, etc. Pyridazine compounds
[0104]
Of these, pyrazole compounds and triazole compounds having a 5-membered or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly suitable. These hydrazine derivatives can be used individually by 1 type or in mixture of 2 or more types.
[0105]
Typical examples of the amine compound having active hydrogen that can be used as a part of the active hydrogen-containing compound (F) include the following.
(1) A primary amino group of an amine compound containing one secondary amino group and one or more primary amino groups, such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, A compound modified with aldimine, ketimine, oxazoline or imidazoline by heat reaction with aldehyde or carboxylic acid at a temperature of about 100 to 230 ° C., for example;
[0106]
(2) Secondary monoamines such as diethylamine, diethanolamine, di-n- or -iso-propanolamine, N-methylethanolamine, N-ethylethanolamine;
(3) Secondary amine-containing compound obtained by adding a monoalkanolamine such as monoethanolamine and dialkyl (meth) acrylamide by Michael addition reaction;
(4) A compound obtained by modifying the primary amino group of an alkanolamine such as monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol, 2-hydroxy-2 '(aminopropoxy) ethyl ether to ketimine;
[0107]
The quaternary chlorinating agent that can be used as a part of the active hydrogen-containing compound (F) is a hydrazine derivative or a tertiary amine that does not have active hydrogen, and is not reactive with an epoxy group by itself. In order to be able to react with the acid. The quaternary chlorinating agent reacts with an epoxy group in the presence of water as necessary to form a quaternary salt with the epoxy group-containing resin.
The acid used to obtain the quaternary chlorinating agent may be any of organic acids such as acetic acid and lactic acid, and inorganic acids such as hydrochloric acid. Examples of the hydrazine derivative having no active hydrogen used for obtaining a quaternary chlorinating agent include 3,6-dichloropyridazine, and examples of the tertiary amine include dimethylethanolamine, triethylamine, Examples include trimethylamine, triisopropylamine, and methyldiethanolamine.
[0108]
The reaction product of the film-forming organic resin (E) and the active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which a part or all of the compounds have active hydrogen is the film-forming organic resin (E) and active hydrogen. It is obtained by reacting the containing compound (F) at 10 to 300 ° C., preferably 50 to 150 ° C., for about 1 to 8 hours.
This reaction may be performed by adding an organic solvent, and the type of the organic solvent to be used is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone, cyclohexanone; ethanol, butanol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether , Propylene glycol, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and other alcohols and ethers containing hydroxyl groups; ethyl acetate, butyl acetate, ethylene glycol monobutyl ether acetate and other esters; toluene, xylene Aromatic hydrocarbons etc. Illustration can, it is possible to use one or more of these. Of these, ketone-based or ether-based solvents are particularly preferred from the standpoints of solubility with an epoxy resin and film-forming properties.
[0109]
The blending ratio of the film-forming organic resin (E) and the active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which a part or all of the compounds have active hydrogen is a ratio of solid content to the film-forming organic resin (E ) The active hydrogen-containing compound (F) is preferably 0.5 to 20 parts by mass, particularly preferably 1.0 to 10 parts by mass with respect to 100 parts by mass.
When the film-forming organic resin (E) is an epoxy group-containing resin (H), the blending ratio of the epoxy group-containing resin (H) and the active hydrogen-containing compound (F) is the active hydrogen-containing compound (F ) And the number of epoxy groups in the epoxy group-containing resin (H) [number of active hydrogen groups / number of epoxy groups] is 0.01 to 10, more preferably 0.1 to 8, and still more preferably. It is appropriate to set it to 0.2-4 from points, such as corrosion resistance.
[0110]
Moreover, the ratio of the hydrazine derivative (G) having active hydrogen in the active hydrogen-containing compound (F) is 10 to 100 mol%, more preferably 30 to 100 mol%, and further preferably 40 to 100 mol%. Is appropriate. If the ratio of the hydrazine derivative (G) having active hydrogen is less than 10 mol%, the organic film cannot be provided with a sufficient rust prevention function, and the resulting rust prevention effect is simply mixing the film-forming organic resin and the hydrazine derivative. It is no different from the case of using it.
[0111]
In the present invention, in order to form a dense barrier film, it is desirable to mix a curing agent in the resin composition and heat cure the organic film (upper layer film).
As a curing method for forming a resin composition film, (1) a curing method using a urethanization reaction between an isocyanate and a hydroxyl group in a base resin, and (2) 1 selected from melamine, urea and benzoguanamine An etherification reaction between an alkyl etherified amino resin obtained by reacting a monohydric alcohol having 1 to 5 carbon atoms with a part or all of a methylol compound obtained by reacting formaldehyde with a seed or more and a hydroxyl group in a base resin. The curing method to be used is suitable, and among these, it is particularly preferable to use a urethanization reaction between isocyanate and a hydroxyl group in the base resin as a main reaction.
[0112]
The polyisocyanate compound used in the curing method (1) above is composed of an aliphatic, alicyclic (including heterocyclic) or aromatic isocyanate compound having at least two isocyanate groups in one molecule, or many of these compounds. It is a compound that has been partially reacted with a monohydric alcohol. Examples of such polyisocyanate compounds include the following.
(1) m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, o- or p-xylylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate
[0113]
(2) The compound of (1) above or a mixture thereof and a polyhydric alcohol (dihydric alcohols such as ethylene glycol and propylene glycol; trihydric alcohols such as glycerin and trimethylolpropane; tetrahydric alcohols such as pentaerythritol; A reaction product with a hexahydric alcohol such as sorbitol and dipentaerythritol), in which at least two isocyanates remain in one molecule
These polyisocyanate compounds can be used individually by 1 type or in mixture of 2 or more types.
[0114]
Moreover, as a protective agent (blocking agent) of a polyisocyanate compound, for example,
(1) Aliphatic monoalcohols such as methanol, ethanol, propanol, butanol, octyl alcohol
(2) Monoethers of ethylene glycol and / or diethylene glycol, for example, monoethers such as methyl, ethyl, propyl (n-, iso), butyl (n-, iso, sec)
(3) Aromatic alcohols such as phenol and cresol
(4) Oxime such as acetoxime and methyl ethyl ketone oxime
A polyisocyanate compound that is stably protected at least at room temperature can be obtained by reacting one or more of these with the polyisocyanate compound.
[0115]
Such polyisocyanate compound (I) is (E) / (I) = 95/5 to 55/45 (weight ratio of non-volatile content), preferably (to the film-forming organic resin (E) as a curing agent, It is suitable to mix | blend in the ratio of E) / (I) = 90 / 10-65 / 35. The polyisocyanate compound has water absorption, and if it is blended exceeding (E) / (I) = 55/45, the adhesion of the upper layer film is deteriorated. Furthermore, when top coating is performed on the upper layer film, the unreacted polyisocyanate compound moves into the coating film, which causes inhibition of curing of the coating film and poor adhesion. From such a viewpoint, the blending amount of the polyisocyanate compound (I) is preferably (E) / (I) = 55/45 or less.
[0116]
The film-forming organic resin (E) is sufficiently crosslinked by the addition of the crosslinking agent (curing agent) as described above, but it is desirable to use a known curing accelerating catalyst in order to further increase the low temperature crosslinking property. Examples of the curing accelerating catalyst include N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, and bismuth nitrate.
For example, when an epoxy group-containing resin is used for the film-forming organic resin (E), a known acrylic, alkyd, polyester, or other resin is mixed with the epoxy group-containing resin for the purpose of improving some physical properties such as adhesion. It can also be used.
[0117]
For the purpose of improving corrosion resistance, the upper layer film may contain a non-chromium rust preventive additive as necessary. By including such a non-chromium-based anticorrosive additive in the upper layer film, more excellent anticorrosion performance can be obtained.
In particular, it is preferable to use at least one selected from the following (e1) to (e5) as the non-chromium-based rust preventive additive.
(E1) Silicon oxide
(E2) Calcium or calcium compound
(E3) Insoluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing S atom selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams
The details and anticorrosion mechanism of the non-chromium-based anticorrosive additives (e1) to (e5) are as described above for the surface treatment film.
[0118]
The compounding amount of the non-chromium rust preventive additive is 0.1 to 50 parts by mass, preferably 0.5 to 30 parts by mass, relative to 100 parts by mass of the solid content of the resin composition for film formation. The part is appropriate. If the blending amount of this non-chromium rust preventive additive is less than 0.1 parts by mass, the effect of improving corrosion resistance after alkali degreasing cannot be sufficiently obtained. On the other hand, if it exceeds 50 parts by mass, paintability, workability, and welding This is not preferable because the corrosion resistance is deteriorated as well as the property.
Two or more rust preventive additives (e1) to (e5) may be added in combination. In this case, since the inherent anticorrosive action is combined, higher corrosion resistance can be obtained. In particular, calcium ion-exchanged silica is used as the component (e1), and one or more of the components (e3), (e4), and (e5), particularly preferably the components (e3) to (e5). When all are added in combination, particularly excellent corrosion resistance is obtained.
[0119]
In addition to the above anticorrosive additive components, the upper layer film also contains other oxide fine particles (eg, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide), phosphomolybdic acid as a corrosion inhibitor. Salts (for example, aluminum phosphomolybdate), organic phosphoric acid and its salts (for example, phytic acid, phytate, phosphonic acid, phosphonate, and metal salts thereof, alkali metal salts, alkaline earth metal salts, etc.) ), Organic inhibitors (for example, hydrazine derivatives, thiol compounds, dithiocarbamates, etc.) can be added.
[0120]
If necessary, a solid lubricant can be blended in the upper film for the purpose of improving the workability of the film.
Examples of the solid lubricant applicable to the present invention include the following, and one or more of these can be used. .
(1) Polyolefin wax, paraffin wax: For example, polyethylene wax, synthetic paraffin, natural paraffin, micro wax, chlorinated hydrocarbon, etc.
(2) Fluorine resin fine particles: For example, polyfluoroethylene resin (polytetrafluoroethylene resin, etc.), polyvinyl fluoride resin, polyvinylidene fluoride resin, etc.
[0121]
In addition, fatty acid amide compounds (eg, stearic acid amide, palmitic acid amide, methylene bis stearoamide, ethylene bis stearoamide, oleic acid amide, esylic acid amide, alkylene bis fatty acid amide), metal Soaps (eg, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc.), metal sulfides (eg, molybdenum disulfide, tungsten disulfide, etc.), graphite, graphite fluoride, boron nitride, polyalkylene glycol, You may use 1 type, or 2 or more types, such as an alkali metal sulfate.
[0122]
Among the above solid lubricants, polyethylene wax and fluororesin fine particles (in particular, polytetrafluoroethylene resin fine particles) are preferable.
Examples of the polyethylene wax include Celite dust 9615A, Celite dust 3715, Celite dust 3620, Celidust 3910 (all trade names) manufactured by Hoechst, Sun wax 131-P and Sun wax 161-P manufactured by Sanyo Chemical Co., Ltd. (Trade name), Chemipearl W-100, Chemipearl W-200, Chemipearl W-500, Chemipearl W-800, Chemipearl W-950 (all trade names) manufactured by Mitsui Petrochemical Co., Ltd. can be used.
[0123]
The fluororesin fine particles are most preferably tetrafluoroethylene fine particles. For example, Lubron L-2, Lubron L-5 (both trade names) manufactured by Daikin Industries, Ltd., MP1100 manufactured by Mitsui DuPont Co., Ltd. MP1200 (all trade names), Fullon Dispersion AD1, Fullon Dispersion AD2, Fullon L141J, Fullon L150J, and Fullon L155J (all trade names) manufactured by Asahi IC Fluoropolymers Co., Ltd. are suitable.
Among these, a particularly excellent lubricating effect can be expected by the combined use of polyolefin wax and tetrafluoroethylene fine particles.
[0124]
The blending amount of the solid lubricant in the upper film is 1 to 30 parts by mass (solid content), preferably 1 to 10 parts by mass (solid) with respect to 100 parts by mass (solid content) of the resin composition for film formation. Minutes). If the blending amount of the solid lubricant is less than 1 part by mass, the lubricating effect is poor. On the other hand, if the blending amount exceeds 30 parts by mass, the paintability is lowered, which is not preferable.
[0125]
The upper layer film of the surface-treated steel sheet of the present invention is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) comprising a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. (Resin composition) as a main component, and a curing agent, a non-chromium anticorrosive additive, a solid lubricant, etc. are added to this as necessary, and if necessary, an organic coloring pigment as an additive (For example, condensed polycyclic organic pigments, phthalocyanine organic pigments, etc.), colored dyes (for example, organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.), inorganic pigments (for example, titanium oxide, etc.), chelating agents (For example, thiol), conductive pigment (for example, metal powder such as zinc, aluminum, nickel, iron phosphide, antimony-doped tin oxide, etc.), coupling agent (for example, silane) Coupling agent, titanium coupling agent) may be added to one or more of melamine-cyanuric acid adduct.
[0126]
Moreover, the coating composition for film formation containing the said main component and an additional component normally contains a solvent (an organic solvent and / or water), and also a neutralizer etc. are added as needed.
The organic solvent is not particularly limited as long as it can dissolve or disperse the reaction product of the film-forming organic resin (E) and the active hydrogen-containing compound (F), and can be prepared as a coating composition. The various organic solvents exemplified above can be used.
The neutralizing agent is blended as necessary to neutralize the film-forming organic resin (E) to make it water-based. When the film-forming organic resin (E) is a cationic resin, Acids such as acetic acid, lactic acid and formic acid can be used as a neutralizing agent.
The dry film thickness of the upper layer film is 0.5 to 2.0 μm, preferably 0.5 to 1.5 μm. When the film pressure of the upper film is less than 0.5 μm, the corrosion resistance is insufficient, while when the film thickness exceeds 2.0 μm, the weldability and electrodeposition coating properties are degraded.
Further, from the viewpoint of weldability and electrodeposition coating properties, the total film thickness of the surface treatment film of the first layer and the upper film of the second layer is preferably 2.0 μm or less.
[0127]
Next, the manufacturing method of the surface treatment steel plate of this invention is demonstrated.
In order to form the surface treatment film on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet, the surface treatment composition (treatment liquid) having the above-described composition is applied to the surface of the plated steel sheet so that the dry film thickness is in the above range. Apply and heat dry without rinsing.
[0128]
As a method for forming the surface treatment composition on the surface of the plated steel sheet, any of a coating method, a dipping method, and a spray method may be used. As a coating treatment method, any method such as a roll coater (3-roll method, 2-roll method, etc.), a squeeze coater, or a die coater may be used. In addition, after the coating process or dipping process using a squeeze coater or the like, or the spray process, the coating amount can be adjusted, the appearance can be made uniform, and the film thickness can be made uniform by an air knife method or roll drawing method.
[0129]
After coating the surface treatment composition, drying is performed without washing with water. As the heating and drying means, a dryer, a hot air furnace, a high frequency induction heating furnace, an infrared furnace or the like can be used. Heat drying is preferably performed in the range of 30 to 150 ° C., preferably 40 to 140 ° C., at the ultimate plate temperature. If the heating and drying temperature is less than 30 ° C., a large amount of moisture remains in the film, resulting in insufficient corrosion resistance. In addition, when the heating and drying temperature exceeds 150 ° C., not only is it uneconomical, but defects occur in the film and the corrosion resistance decreases. Moreover, since it becomes impossible to apply to a BH steel plate when heat drying temperature exceeds 150 degreeC, it is unpreferable.
An upper layer film (organic resin film) is formed as the second layer film on the upper layer of the surface treatment film formed as described above. The coating composition for the second layer film is applied to the surface-treated film surface so as to have the above-described film thickness, and is dried by heating. Application | coating of a coating composition should just be performed according to the method used for formation of the surface treatment film mentioned above.
[0130]
After application of the coating composition, drying is usually performed without washing with water, but a washing process may be performed after application of the coating composition. For the heat drying treatment, a dryer, a hot air furnace, a high-frequency induction heating furnace, an infrared furnace, or the like can be used. Heat drying is preferably performed in the range of 30 to 150 ° C., preferably 40 to 140 ° C., at the ultimate plate temperature. If the heating and drying temperature is less than 30 ° C., a large amount of moisture remains in the film, resulting in insufficient corrosion resistance. In addition, when the heating and drying temperature exceeds 150 ° C., not only is it uneconomical, but defects occur in the film and the corrosion resistance decreases. Moreover, since it becomes impossible to apply to a BH steel plate when heat drying temperature exceeds 150 degreeC, it is unpreferable.
[0131]
Therefore, the manufacturing method of the surface treatment steel plate of this invention and its preferable embodiment are as follows.
[1] A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and dried at a temperature of 30 to 150 ° C. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) A polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet, characterized in that an upper film is formed by applying a coating composition comprising: and drying at a final plate temperature of 30 to 150 ° C. Manufacturing method.
[0132]
[2] A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and is dried at a temperature of 30 to 150 ° C. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) A polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified Obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion in which resin is dispersed in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet, characterized in that an upper film is formed by applying a coating composition comprising: and drying at a final plate temperature of 30 to 150 ° C. Manufacturing method.
[0133]
[3] A bisphenol A type epoxy resin having an epoxy equivalent of 150 to 5000 in the production method of [1] or [2], wherein the epoxy group-containing resin (B) for obtaining the aqueous epoxy resin dispersion of component (a) is The number average molecular weight is 1500-10000, The manufacturing method of the highly corrosion-resistant surface treatment steel plate characterized by the above-mentioned.
[4] In the production method of any one of [1] to [3], the aqueous epoxy resin dispersion of component (a) further contains a curing agent having a group that crosslinks with a hydroxyl group. A method for producing a corrosion-resistant surface-treated steel sheet.
[5] In the production method according to any one of [1] to [4], the surface treatment composition for forming a surface treatment film further comprises a water-soluble phosphate, and an aqueous epoxy resin dispersion of component (a). The manufacturing method of the highly corrosion-resistant surface-treated steel plate characterized by containing 0.1-60 mass parts of solid content with respect to 100 mass parts of solid content.
[0134]
[6] In the production method of [5], the surface treatment composition for forming a surface treatment film is a water-soluble phosphate, and a cationic component and P₂O₅Component molar ratio [cation] / [P₂O₅] Is a highly corrosion-resistant surface characterized by containing a water-soluble phosphate having a cation species of at least one selected from Mn, Mg, Al, and Ni A method for producing a treated steel sheet.
[7] In the production method according to any one of [1] to [6], the surface treatment composition for forming a surface treatment film further includes a non-chromium rust preventive additive, and an aqueous epoxy resin dispersion of component (a) The manufacturing method of the highly corrosion-resistant surface-treated steel plate characterized by containing 0.1-50 mass parts in the ratio of solid content with respect to 100 mass parts of solid content of a liquid.
[8] In the production method according to any one of [1] to [7], the coating composition for forming the upper film further includes a non-chromium rust preventive additive with respect to 100 parts by mass of the solid content of the resin composition. The manufacturing method of the highly corrosion-resistant surface treatment steel plate characterized by containing 0.1-50 mass parts in the ratio of solid content.
[0135]
[9] In the production method of [7] or [8] above, a surface treatment composition for forming a surface treatment film and / or a coating composition for forming an upper film is used as a non-chromium rust preventive additive as described below ( A method for producing a highly corrosion-resistant surface-treated steel sheet, comprising one or more rust preventive additives selected from e1) to (e5).
(E1) Silicon oxide
(E2) Calcium and / or calcium compounds
(E3) Insoluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing S atom selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams
[10] In the production method according to any one of [1] to [9], the component (b) includes at least one silane coupling agent having an amino group as a reactive functional group as the silane coupling agent. A method for producing a highly corrosion-resistant surface-treated steel sheet. [11] In the production method according to any one of [1] to [10], the coating composition for forming an upper film further includes a solid lubricant with a solid content of 100 parts by mass of the solid content of the resin composition. The manufacturing method of the highly corrosion-resistant surface-treated steel plate characterized by containing 1-30 mass parts in a ratio.
[0136]
In addition, the surface treatment film and the upper layer film described above may be formed on either one side or both sides of the plated steel sheet. As a combination of the film forms on the front and back surfaces of the plated steel sheet, for example, surface treatment film + upper layer film / no treatment, The surface treatment film + upper layer film / surface treatment film, surface treatment film + upper layer film / surface treatment film + upper layer film, and the like can be used.
[0137]
【Example】
[Example 1]
The surface treatment composition for forming the first layer uses a water-soluble or water-dispersible epoxy resin shown in Table 2 as a resin composition, and a silane coupling agent (Table 3), phosphoric acid or hexafluorometal acid ( Table 4), a water-soluble phosphate (Table 5), and a non-chromium rust preventive additive (Table 6) are appropriately blended, and stirred for a predetermined time using a coating disperser (sand grinder), and then a surface treatment composition. Was prepared.
The water-soluble or water-dispersible epoxy resins shown in Table 2 were produced as follows.・ Manufacture of polyalkylene glycol-modified epoxy resin
<Production Example 1>
To a glass four-necked flask equipped with a thermometer, a stirrer, and a condenser tube, 1688 g of polyethylene glycol having a number average molecular weight of 4000 and 539 g of methyl ethyl ketone were added and stirred and mixed at 60 ° C., and then 171 g of tolylene diisocyanate was added. In addition, after reacting for 2 hours, 1121 g of Epicoat 834X90 (epoxy resin, manufactured by Shell Japan, epoxy equivalent 250), 66 g of diethyleneglycolethyl ether and 1.1 g of 1% dibutyltin dilaurate solution were added, and further reacted for 2 hours. I let you. Thereafter, the temperature was raised to 80 ° C. and reacted for 3 hours to confirm that the isocyanate value was 0.6 or less. Thereafter, the temperature was raised to 90 ° C., and methyl ethyl ketone was removed by distillation under reduced pressure until the solid content concentration reached 81.7%. After removal, 659 g of propylene glycol monomethyl ether and 270 g of deionized water were added and diluted to obtain a polyalkylene glycol-modified epoxy resin solution A1 having a solid concentration of 76%.
[0138]
・ Manufacture of aqueous epoxy resin dispersion
<Production Example 2>
2029 g of EP1004 (epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 1000) and 697 g of propylene glycol monobutyl ether were charged into a four-necked flask, heated to 110 ° C. and completely dissolved in 1 hour. After 1180 g of the polyalkylene glycol-modified epoxy resin solution A1 obtained in Production Example 1 and 311.7 g of 3-amino-1,2,4-triazole (molecular weight 84) were added to this product and reacted at 100 ° C. for 5 hours. Then, 719.6 g of propylene glycol monobutyl ether was added to obtain a resin solution D1.
257.6 g of the above resin solution D1 was mixed with 50 g of MF-K60X (isocyanate curing agent, manufactured by Asahi Kasei Kogyo Co., Ltd.) and 0.3 g of Scat24 (curing catalyst), and after stirring well, 692.1 g of water was added dropwise little by little. Mixing and stirring were performed to obtain an aqueous epoxy resin dispersion E1.
[0139]
<Production Example 3> (Aqueous epoxy resin dispersion containing no hydrazine derivative)
2029 g of EP1004 (epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 1000) and 697 g of propylene glycol monobutyl ether were charged into a four-necked flask, heated to 110 ° C. and completely dissolved in 1 hour. 1180 g of the polyalkylene glycol-modified epoxy resin solution A1 obtained in Production Example 1 and 527.0 g of propylene glycol monobutyl ether were added to this to obtain a resin solution D2.
To 257.6 g of the above resin solution D2, 50 g of MF-K60X (isocyanate curing agent, manufactured by Asahi Kasei Kogyo Co., Ltd.) and 0.3 g of Scat24 (curing catalyst) were mixed and stirred well, and then 692.1 g of water was dropped and mixed little by little. The mixture was stirred to obtain an aqueous epoxy resin dispersion E2.
[0140]
As the coating composition for forming the second layer, the resin composition shown in Table 7 is used, and a non-chromium rust preventive additive (Table 6) and a solid lubricant (Table 8) are appropriately blended into the coating composition. The mixture was stirred for a predetermined time using a dispersing machine (sand grinder) to prepare a coating composition. The base resin (reaction product) of the resin composition shown in Table 7 was synthesized as follows.
<Synthesis Example 1>
EP828 (manufactured by Yuka Shell Epoxy Co., Epoxy Equivalent 187) 1870 parts, bisphenol A 912 parts, tetraethylammonium bromide 2 parts, methyl isobutyl ketone 300 parts are charged into a four-necked flask and heated to 140 ° C. and reacted for 4 hours. An epoxy resin having an epoxy equivalent of 1391 and a solid content of 90% was obtained. To this product, 1500 parts of ethylene glycol monobutyl ether was added and cooled to 100 ° C., 96 parts of 3,5-dimethylpyrazole (molecular weight 96) and 129 parts of dibutylamine (molecular weight 129) were added, and the epoxy group disappeared. After reacting for 6 hours, 205 parts of methyl isobutyl ketone was added while cooling to obtain a pyrazole-modified epoxy resin having a solid content of 60%. This is designated as resin composition (1). This resin composition (1) is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound containing 50 mol% of a hydrazine derivative (G) having active hydrogen.
[0141]
<Synthesis Example 2>
4000 parts of EP1007 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 2000) and 2239 parts of ethylene glycol monobutyl ether were charged into a four-necked flask and heated to 120 ° C. to completely dissolve the epoxy resin in 1 hour. This was cooled to 100 ° C., 168 parts of 3-amino-1,2,4-triazole (molecular weight 84) was added, and the mixture was allowed to react for 6 hours until the epoxy group disappeared. A triazole-modified epoxy resin having a solid content of 60% was obtained. This is designated as resin composition (2). This resin composition (2) is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound containing 100 mol% of a hydrazine derivative (G) having active hydrogen.
[0142]
<Synthesis Example 3>
222 parts of isophorone diisocyanate (isocyanate equivalent 111) and 34 parts of methyl isobutyl ketone were charged into a four-necked flask and maintained at 30 to 40 ° C., and 87 parts of methyl ethyl ketoxime (molecular weight 87) was added dropwise over 3 hours. By maintaining the time, a partially blocked isocyanate having an isocyanate equivalent of 309 and a solid content of 90% was obtained.
Subsequently, 1428 parts of EP828 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 187), 684 parts of bisphenol A, 1 part of tetraethylammonium bromide and 241 parts of methyl isobutyl ketone were charged into a four-necked flask and heated to 140 ° C. for 4 hours. Reaction was performed to obtain an epoxy resin having an epoxy equivalent of 1090 and a solid content of 90%. To this, 1000 parts of methyl isobutyl ketone was added and then cooled to 100 ° C., and 202 parts of 3-mercapto-1,2,4-triazole (molecular weight 101) was added and reacted for 6 hours until the epoxy group disappeared. Thereafter, 230 parts of the partially blocked isocyanate having a solid content of 90% was added and reacted at 100 ° C. for 3 hours to confirm that the isocyanate group had disappeared. Further, 461 parts of ethylene glycol monobutyl ether was added to obtain a triazole-modified epoxy resin having a solid content of 60%. This is designated as resin composition (3). This resin composition (3) is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound containing 100 mol% of a hydrazine derivative (G) having active hydrogen.
[0143]
<Synthesis Example 4>
EP828 (manufactured by Yuka Shell Epoxy Co., Epoxy Equivalent 187) 1870 parts, bisphenol A 912 parts, tetraethylammonium bromide 2 parts, methyl isobutyl ketone 300 parts are charged into a four-necked flask and heated to 140 ° C. and reacted for 4 hours. An epoxy resin having an epoxy equivalent of 1391 and a solid content of 90% was obtained. To this was added 1500 parts of ethylene glycol monobutyl ether, cooled to 100 ° C., added with 258 parts of dibutylamine (molecular weight 129), reacted for 6 hours until the epoxy group disappeared, and then cooled with methyl isobutyl. 225 parts of ketone was added to obtain an epoxyamine adduct having a solid content of 60%. This is designated as resin composition (4). This resin composition (4) is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound that does not contain a hydrazine derivative (G) having active hydrogen.
[0144]
The plated steel sheet shown in Table 1, which is a plated steel sheet for home appliances, building materials, and automobile parts based on cold-rolled steel sheets, was used as a processing original sheet. In addition, the thing of predetermined | prescribed board thickness was employ | adopted for the board thickness of the steel plate according to the objective of evaluation. After the surface of this plated steel sheet was subjected to alkali degreasing treatment, washed with water and dried, the surface treatment composition for forming the first layer was applied with a roll coater and dried by heating at various temperatures. The film thickness of the film was adjusted by the solid content (heating residue) of the surface treatment composition or coating conditions (rolling force of the roll, rotation speed, etc.).
Next, the coating composition for forming the second layer was applied by a roll coater and dried by heating at various temperatures. The film thickness of the film was adjusted by the solid content (heating residue) of the coating composition or application conditions (rolling force of roll, rotation speed, etc.).
[0145]
Tables 9 to 22 show the results of evaluating the coating composition and quality performance (corrosion resistance, post-processing corrosion resistance, weldability, electrodeposition coating property) of the obtained surface-treated steel sheet. The quality performance was evaluated as follows.
(1) Corrosion resistance
Each sample was subjected to the following combined cycle test (CCT) and evaluated by the white rust generation area ratio and the red rust generation area ratio after 30 cycles.
Salt spray (based on JIS Z 2371): 4 hours
↓
Dry (60 ° C): 2 hours
↓
Wet (50 ° C., 95% RH): 2 hours
The evaluation criteria are as follows.
◎: White rust generation area ratio is less than 10%
○: White rust generation area rate of 10% or more and less than 30%
○-: Red rust is not generated when white rust generation area ratio is 30% or more
Δ: Red rust is generated and the area ratio of red rust is less than 10%
×: Red rust occurrence area ratio 10% or more
[0146]
(2) Corrosion resistance after processing
For each sample, after adding deformation and sliding with a draw bead according to the following conditions, this sample was degreased at 45 ° C. for 2 minutes using “FC-4460” manufactured by Nihon Parkerizing Co., Ltd. CCT performed by said "(1) Corrosion resistance" was given, and it evaluated by the white rust generation | occurrence | production area ratio and red rust generation | occurrence | production area ratio after 18 cycles progress.
Pressing load: 800kgf
Drawing speed: 1000mm / min
Bead shoulder R: Male side 5mmR, Female side 5mmR
Pushing depth: 7mm
Oil used: Preton R-352L
The evaluation criteria are as follows.
◎: White rust generation area ratio is less than 10%
○: White rust generation area rate of 10% or more and less than 30%
○-: White rust generation area ratio of 30% or more, no red rust generation
Δ: Red rust is generated and the area ratio of red rust is less than 10%
×: Red rust occurrence area ratio 10% or more
[0147]
(3) Weldability
About each sample, the welding test of the continuous spot property was performed on the conditions of use electrode: CF type | mold Cr-Cu electrode, applied pressure: 200kgf, energization time: 10 cycles / 50Hz, and welding current: 10kA, and evaluated by the number of continuous spots. The evaluation criteria are as follows.
◎: 2000 points or more
○: 1000 points or more and less than 2000 points
Δ: 500 points or more and less than 1000 points
×: Less than 500 points
(4) Electrodeposition paintability
Each sample was coated with a cationic electrodeposition paint (“GT-10” manufactured by Kansai Paint Co., Ltd.) so as to have a film thickness of 30 μm, and then baked at 130 ° C. for 30 minutes. The coated sample was immersed in boiling water for 2 hours, immediately cut in a grid pattern (10 × 10, 1 mm interval), attached and peeled with an adhesive tape, and the peeled area ratio of the coating film was measured. The evaluation criteria are as follows.
: No peeling
○: Peel area ratio less than 5%
Δ: peeling area ratio 5% or more and less than 20%
X: Peeling area ratio 20% or more
[0148]
[Table 1]

[0149]
[Table 2]

[0150]
[Table 3]

[0151]
[Table 4]

[0152]
[Table 5]

[0153]
[Table 6]

[0154]
[Table 7]

[0155]
[Table 8]

[0156]
In addition, * 1 to * 10 described in Table 9 to Table 22 indicate the following contents.
* 1: No. described in Table 1. (Plated steel sheet)
* 2: No. in Table 2 (Water-soluble or water-dispersible epoxy resin)
* 3: No. described in Table 3 (Silane coupling agent)
* 4: No. in Table 4 (Phosphoric acid or hexafluorometal acid)
* 5: No. in Table 5 (Water-soluble phosphate)
* 6: No. in Table 6 (Anti-rust additive)
* 7: parts by mass (for components other than water-soluble or water-dispersible epoxy resins, parts by mass relative to 100 parts by mass of the solid content of the water-soluble or water-dispersible epoxy resin)
* 8: No. in Table 7 (Resin composition)
* 9: No. in Table 8 (Solid lubricant)
* 10: parts by mass (for components other than organic resins, parts by mass relative to 100 parts by mass of solid content of organic resin)
[0157]
[Table 9]

[0158]
[Table 10]

[0159]
[Table 11]

[0160]
[Table 12]

[0161]
[Table 13]

[0162]
[Table 14]

[0163]
[Table 15]

[0164]
[Table 16]

[0165]
[Table 17]

[0166]
[Table 18]

[0167]
[Table 19]

[0168]
[Table 20]

[0169]
[Table 21]

[0170]
[Table 22]

[0171]
[Example 2]
In Examples 1 to 3 of the present invention for No. 1 surface treatment film, No. No. 1 in Table 3 for the aqueous epoxy resin dispersion of No. 1. No. 1 in Table 2 was used in the comparative example, and the surface treatment composition containing the silane coupling agent of No. 1 and phosphoric acid was used. A surface treatment composition comprising only one aqueous epoxy resin dispersion was used. These surface treatment compositions were subjected to alkaline degreasing treatment, washed with water and dried and then No. 1 in Table 1. The coated steel sheet 1 was coated with a roll coater and dried by heating at 140 ° C. to form a surface treatment film having a thickness of 0.5 μm. Next, as examples for the upper layer coating of the second layer, both the examples of the present invention and the comparative examples are No. 1 in [Example 1]. 3 (Table 10), the same coating composition was applied to the surface treatment film as the first layer by a roll coater, and dried by heating at 140 ° C. to an upper layer having a thickness of 1.5 μm. A film was formed.
[0172]
The obtained surface-treated steel sheet was evaluated for corrosion resistance and post-processing corrosion resistance under the same test conditions and evaluation criteria as in [Example 1]. The results are shown in Table 23 together with the film configurations of the first layer and the second layer.
・ Comparative example
In the comparative example of Table 23, since the surface treatment film of the first layer is composed only of an organic resin barrier layer, the corrosion resistance and post-processing corrosion resistance are insufficient.
FIG. 1 shows a film cross-sectional electron micrograph (bright field image) of a film corresponding to the surface treatment film of the comparative example. Sample preparation and measurement were performed under the conditions described above.
[0173]
-Invention Example 1
Invention Example 1 in Table 23 has excellent corrosion resistance and post-processing corrosion resistance as compared with the comparative example.
FIG. 2 shows a cross-sectional electron micrograph (bright field image) of the film corresponding to the surface-treated film of Example 1 of the present invention, and FIG. 3 also shows the result of composition analysis of the film cross-section (line analysis: vertical axis indicates atomic concentration) Note that the C concentration is mostly overscale, so the description is omitted (the same applies to FIGS. 5 and 7 described later). Sample preparation and measurement were performed under the conditions described above (the same applies to FIGS. 4 to 7 described later). According to these, a surface treatment film is formed in which the lower layer portion includes P, Zn, and O, and an equimolar amount of Zn and P includes a compound layer (amorphous compound layer), and the upper layer portion includes an organic resin matrix layer. I know that. According to the electron diffraction pattern, the compound layer is amorphous. In FIG. 3 (the same applies to FIGS. 5 and 7 to be described later), Zn and P in the compound layer are separated from equimolar to Zn-rich on the galvanized film side because the probe diameter of the electron beam is finite. This is because the galvanized layer itself and the compound layer are simultaneously included in the probe diameter at the compound layer / plated layer interface.
[0174]
-Invention Example 2
Invention Example 2 in Table 23 has further superior corrosion resistance and post-processing corrosion resistance compared to Invention Example 1.
4 is a film cross-sectional electron micrograph of a film corresponding to the surface treatment film of Example 2 of the present invention (bright-field image. The arrow in FIG. 4 indicates a deposited compound, and the oblique broken line indicates the line analysis position in FIG. Similarly, FIG. 5 shows the composition analysis results of the film cross section (the downward arrow in the graph corresponds to the position of the precipitated compound). According to these, like Example 1 of the present invention, a compound layer (amorphous compound layer) containing P, Zn and O and containing equimolar amounts of Zn and P is formed in the lower layer portion of the surface treatment film. Yes. Furthermore, in this invention example 2, the compound containing P, Zn, and O has precipitated in the surface treatment film. According to the electron diffraction pattern, the compound layer and the deposited compound are amorphous.
[0175]
-Invention Example 3
Invention Example 3 in Table 23 has further superior corrosion resistance and post-processing corrosion resistance compared to Invention Example 2.
6 is a cross-sectional electron micrograph of a film corresponding to the surface treatment film of Example 3 of the present invention (bright field image. The arrow in FIG. 6 indicates a deposited compound, and the oblique broken line indicates the line analysis position in FIG. Similarly, FIG. 7 shows the composition analysis results of the film cross section (the downward arrows in the graph correspond to the positions of the precipitated compounds). According to these, similarly to Examples 1 and 2 of the present invention, a compound layer (amorphous compound layer) containing P, Zn and O and containing equimolar amounts of Zn and P is formed in the lower layer portion of the surface treatment film. Has been. Furthermore, in this invention example 3, the compound containing Zn, P, Si, and O has precipitated in the surface treatment film. In addition, these deposited compounds have a Zn / P molar ratio [Zn] / [P] of less than 1.0. According to the electron diffraction pattern, the compound layer and the deposited compound are amorphous.
[0176]
[Table 23]

[0177]
In addition, * 1 to * 7 described in Table 23 indicate the following contents.
* 1: No. in Table 2 (Water-dispersible epoxy resin)
* 2: No. in Table 3 (Silane coupling agent)
* 3: No. described in Table 4 (Phosphoric acid or hexafluorometal acid)
* 4: parts by mass (for components other than the water-dispersible epoxy resin, parts by mass with respect to 100 parts by mass of the solid content of the water-dispersible epoxy resin)
* 5: No. in Table 7 (Resin composition)
* 6: No. in Table 6 (Anti-rust additive)
* 7: parts by mass (for antirust additives, parts by mass relative to 100 parts by mass of solid content of organic resin)
[0178]
【The invention's effect】
As described above, the surface-treated steel sheet according to the present invention has a very excellent flat plate and corrosion resistance after processing, despite having no chromium in the film, and is also excellent in weldability and paintability. For this reason, the surface-treated steel sheet of the present invention is particularly useful for automobile applications.
[Brief description of the drawings]
FIG. 1 is an electron micrograph of a cross-sectional structure of a film corresponding to the surface-treated film of a surface-treated steel sheet of a comparative example in [Example 2].
FIG. 2 is an electron micrograph of the cross-sectional structure of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 1 of the present invention in [Example 2].
FIG. 3 is a graph showing a composition analysis result of a cross section of a film corresponding to the surface-treated film of the surface-treated steel sheet of Example 1 of the present invention in [Example 2].
FIG. 4 is an electron microscopic enlarged photograph of the film cross-sectional structure of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 2 of the present invention in [Example 2].
FIG. 5 is a graph showing the composition analysis result of the film cross-section of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 2 of the present invention in [Example 2].
FIG. 6 is an electron microscopic enlarged photograph of the cross-sectional structure of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 3 of the present invention in [Example 2].
FIG. 7 is a graph showing the composition analysis result of the film cross section of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 3 of the present invention in [Example 2].

Claims (25)

The film thickness formed by applying a surface treatment composition containing the following components (a) to (c) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and drying is 0.01 to 1.0 μm. A surface treatment film of
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion (b) silane obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water Coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion (c) phosphoric acid and / or hexafluorometal acid: 100 parts by mass of the solid content of the aqueous epoxy resin dispersion On the other hand, the main component of the resin composition is 0.1 to 80 parts by mass of the film forming organic resin. An upper layer film comprising a reaction product of (E) and an active hydrogen-containing compound (F) comprising a hydrazine derivative (G) in which some or all of the compounds have active hydrogen, and having a film thickness of 0.5 to 2.0 μm A highly corrosion-resistant surface-treated steel sheet, characterized in that is formed. The film thickness formed by applying and drying the surface treatment composition containing the components (a) to (c) on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet is 0.01 to 1.0 μm. Form a surface treatment film,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified Obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion obtained by dispersing resin in water (b) Silane coupling agent: 1 to 300 parts by mass (c) phosphoric acid and / or hexa per 100 parts by mass of the solid content of the aqueous epoxy resin dispersion Fluorometallic acid: 0.1 to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion On the upper layer of 0 part by mass, the main component of the resin composition is a film-forming organic resin (E) and an active hydrogen-containing compound (F) consisting of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising a reaction product and having a film thickness of 0.5 to 2.0 μm formed thereon. The epoxy group-containing resin (B) for obtaining the aqueous epoxy resin dispersion of component (a) is a bisphenol A type epoxy resin having an epoxy equivalent of 150 to 5000, and its number average molecular weight is 1500 to 10,000. The highly corrosion-resistant surface-treated steel sheet according to claim 1 or 2. The highly corrosion-resistant surface-treated steel sheet according to claim 1, 2 or 3, wherein the aqueous epoxy resin dispersion of component (a) further contains a curing agent having a group that crosslinks with a hydroxyl group. The surface treatment composition for forming a surface treatment film further contains a water-soluble phosphate in an amount of 0.1 to 60 mass in terms of solid content with respect to 100 mass parts of solid content of the aqueous epoxy resin dispersion of component (a). The highly corrosion-resistant surface-treated steel sheet according to claim 1, 2, 3, or 4, characterized by comprising a part. The surface treatment composition for forming the surface treatment film is a water-soluble phosphate, and the molar ratio of the cation component to the P ₂ O ₅ component [cation] / [P ₂ O ₅ ] is 0.4 to 1.0. The highly corrosion-resistant surface-treated steel sheet according to claim 5, wherein the highly corrosion-resistant surface-treated steel sheet comprises a water-soluble phosphate having a cation species of at least one selected from Mn, Mg, Al, and Ni. The surface treatment composition for forming a surface treatment film further contains a non-chromium anticorrosive additive in a proportion of 0.1 to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion of component (a). The highly corrosion-resistant surface-treated steel sheet according to claim 1, comprising 50 parts by mass. The upper layer film further contains 0.1 to 50 parts by mass of a non-chromium rust preventive additive in a solid content ratio with respect to 100 parts by mass of the solid content of the resin composition. The highly corrosion-resistant surface-treated steel sheet according to 3, 4, 5, 6 or 7. The surface treatment composition for forming a surface treatment film and / or the upper film contains one or more rust preventive additives selected from the following (e1) to (e5) as non-chromium rust preventive additives. The highly corrosion-resistant surface-treated steel sheet according to claim 7 or 8.
(E1) silicon oxide (e2) calcium and / or calcium compound (e3) poorly soluble phosphate compound (e4) molybdate compound (e5) selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms The silane coupling agent of component (b) contains at least one silane coupling agent having an amino group as a reactive functional group. The highly corrosion-resistant surface-treated steel sheet according to 7, 8 or 9. The upper layer film further contains 1 to 30 parts by mass of a solid lubricant in a ratio of the solid content to 100 parts by mass of the solid content of the resin composition. , 6, 7, 8, 9 or 10. Highly corrosion-resistant surface-treated steel sheet. (X) an amorphous compound layer containing P, Zn or / and Al, and O on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and (y) a number average molecular weight of 400- Polyalkylene glycol-modified epoxy resin (A) obtained by reacting 20000 polyalkylene glycol, bisphenol-type epoxy resin, active hydrogen-containing compound and polyisocyanate compound, and an epoxy other than the polyalkylene glycol-modified epoxy resin (A) The film thickness is comprised of an organic resin matrix layer comprising a water-dispersible resin obtained by reacting a group-containing resin (B) and a hydrazine derivative (C) having active hydrogen as a matrix, having a film thickness of 0.01 to Having a surface treatment film of 1.0 μm,
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper film having a film thickness of 0.5 to 2.0 μm. On the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, (x) an amorphous compound layer containing P, Zn or / and Al, and O, and (y) a number average molecular weight of 400- Polyalkylene glycol-modified epoxy resin (A) obtained by reacting 20000 polyalkylene glycol, bisphenol-type epoxy resin, active hydrogen-containing compound and polyisocyanate compound, and an epoxy other than the polyalkylene glycol-modified epoxy resin (A) A water-dispersible resin obtained by reacting a group-containing resin (B), a hydrazine derivative (C) having active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C) is used as a matrix. It has a surface treatment film composed of an organic resin matrix layer and a film thickness of 0.01 to 1.0 μm.
On the upper layer, the reaction product of the active hydrogen-containing compound (F), in which the main component of the resin composition is a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper film having a film thickness of 0.5 to 2.0 μm. The high-corrosion-resistant surface-treated steel sheet according to claim 12 or 13, wherein the surface-treated film further contains a silane compound. The highly corrosion-resistant surface-treated steel sheet according to claim 12, 13 or 14, wherein the surface-treated film contains a precipitated compound containing P, Zn or / and Al, and O. The highly corrosion-resistant surface-treated steel sheet according to claim 12, 13, 14 or 15, wherein the surface-treated film contains a precipitation compound containing P, Zn or / and Al, Si and O. A surface-treated steel sheet having a surface-treated film on the surface of a zinc-based plated steel sheet and an upper film on the surface-treated film, wherein the molar ratio [Zn] / [P] of Zn and P in the amorphous compound layer is 0 The highly corrosion-resistant surface-treated steel sheet according to claim 12, 13, 14, 15 or 16, wherein the steel sheet has a thickness of .9 to 1.4. A surface-treated steel sheet having a surface-treated film on the surface of a zinc-based plated steel sheet and an upper layer film on the surface-treated film, the molar ratio of Zn and P in the precipitated compound contained in the surface-treated film [Zn] / [P ] Is 0.9-1.4, The highly corrosion-resistant surface-treated steel sheet according to claim 15, 16 or 17. A surface-treated steel sheet having a surface-treated film on the surface of a zinc-based plated steel sheet and an upper layer film on the surface-treated film, the molar ratio of Zn and P in the precipitated compound contained in the surface-treated film [Zn] / [P ] Is less than 1.0, The highly corrosion-resistant surface-treated steel sheet according to claim 15, 16 or 17. The surface-treated film further contains 0.1 to 50 parts by mass of a non-chromium rust preventive additive in a solid content ratio of 100 parts by mass of the solid content of the organic resin. , 14, 15, 16, 17, 18 or 19 High corrosion resistance surface-treated steel sheet. The upper layer film further contains 0.1 to 50 parts by mass of a non-chromium rust preventive additive in a solid content ratio of 100 parts by mass of the solid content of the resin composition. , 14, 15, 16, 17, 18, 19, or 20 A highly corrosion-resistant surface-treated steel sheet. 21. The surface treatment film and / or the upper film contains one or more rust preventive additives selected from the following (e1) to (e5) as non-chromium rust preventive additives. Or a highly corrosion-resistant surface-treated steel sheet according to 21.
(E1) silicon oxide (e2) calcium and / or calcium compound (e3) poorly soluble phosphate compound (e4) molybdate compound (e5) selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms The upper layer film further contains 1 to 30 parts by mass of a solid lubricant in a ratio of the solid content to 100 parts by mass of the solid content of the resin composition. , 17, 18, 19, 20, 21, or 22. A highly corrosion-resistant surface-treated steel sheet. The coating thickness is obtained by applying a surface treatment composition containing the following components (a) to (c) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and drying at a temperature of an ultimate sheet temperature of 30 to 150 ° C. Forms a surface treatment film of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion (b) silane obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water Coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion (c) phosphoric acid and / or hexafluorometal acid: 100 parts by mass of the solid content of the aqueous epoxy resin dispersion On the other hand, the main component of the resin composition is a film-forming organic resin in an upper layer of 0.1 to 80 parts by mass A coating composition comprising a reaction product of E) and an active hydrogen-containing compound (F) comprising a hydrazine derivative (G) in which some or all of the compounds have active hydrogen is applied, and the ultimate plate temperature is 30 to 150 ° C. A method for producing a highly corrosion-resistant surface-treated steel sheet, wherein an upper film having a film thickness of 0.5 to 2.0 μm is formed by drying at a temperature of 5 ° C. The coating thickness is obtained by applying a surface treatment composition containing the following components (a) to (c) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and drying at a temperature of an ultimate sheet temperature of 30 to 150 ° C. Forms a surface treatment film of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified Obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion obtained by dispersing resin in water (b) Silane coupling agent: 1 to 300 parts by mass (c) phosphoric acid and / or hexa per 100 parts by mass of the solid content of the aqueous epoxy resin dispersion Fluorometal acid: 0.1 to 8 with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion On the upper layer thereof, the main component of the resin composition is a reaction with an active hydrogen-containing compound (F) comprising a film-forming organic resin (E) and a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface treatment characterized in that a coating composition composed of a product is applied and dried at a final plate temperature of 30 to 150 ° C. to form an upper film with a film thickness of 0.5 to 2.0 μm. A method of manufacturing a steel sheet.

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